Substituted Benzenes: The Subba Reddy Synthesis of 7-Desmethoxyfusarentin

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Ethyl Cyanoacetate ◽  
Strong Acid ◽  
State University ◽  
Max Planck ◽  
University Of Texas ◽  
Ru Catalyst ◽  
Aryl Ketones ◽  
Peking University ◽  
University Of Bristol ◽  
The University

Andrey P. A ntonchick of the Max-Planck-Institut Dortmund devised (Org. Lett. 2012, 14, 5518) a protocol for the direct amination of an arene 1 to give the amide 3. Douglass A. Klumpp of Northern University showed (Tetrahedron Lett. 2012, 53, 4779) that under strong acid conditions, an arene 4 could be carboxylated to give the amide 6. Eiji Tayama of Niigata University coupled (Tetrahedron Lett. 2012, 53, 5159) an arene 7 with the α-diazo ester 8 to give 9. Guy C. Lloyd-Jones and Christopher A. Russell of the University of Bristol activated (Science 2012, 337, 1644) the aryl silane 11 to give an intermediate that coupled with the arene 10 to give 12. Ram A. Vishwakarma and Sandip P. Bharate of the Indian Institute of Integrative Medicine effected (Tetrahedron Lett. 2012, 53, 5958) ipso nitration of an areneboronic acid 13 to give 14. Stephen L. Buchwald of MIT coupled (J. Am. Chem. Soc. 2012, 134, 11132) sodium isocyanate with the aryl chloride 15 (aryl triflates also worked well) to give the isocyanate 16, which could be coupled with phenol to give the carbamate or carried onto the unsymmetrical urea. Zhengwu Shen of the Shanghai University of Traditional Chinese Medicine used (Org. Lett. 2012, 14, 3644) ethyl cyanoacetate 18 as the donor for the conversion of the aryl bromide 17 to the nitrile 19. Kuo Chu Hwang of the National Tsig Hua University showed (Adv. Synth. Catal. 2012, 354, 3421) that under the stimulation of blue LED light the Castro-Stephens coupling of 20 with 21 proceeded efficiently at room temperature. Lutz Ackermann of the Georg-August-Universität Göttingen employed (Org. Lett. 2012, 14, 4210) a Ru catalyst to oxidize the amide 23 to the phenol 24. Both Professor Ackermann (Org. Lett. 2012, 14, 6206) and Guangbin Dong of the University of Texas (Angew. Chem. Int. Ed. 2012, 51, 13075) described related work on the ortho hydroxylation of aryl ketones. George A. Kraus of Iowa State University rearranged (Tetrahedron Lett. 2012, 53, 7072) the aryl benzyl ether 25 to the phenol 26. The synthetic utility of the triazene 27 was demonstrated (Angew. Chem. Int. Ed. 2012, 51, 7242) by Yong Huang of the Shenzen Graduate School of Peking University.

C–H Functionalization: The Snyder Synthesis of (+)-Scholarisine A

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Unsaturated Ester ◽  
State University ◽  
University Of Minnesota ◽  
University Of Texas ◽  
Princeton University ◽  
Fe Catalyst ◽  
Peking University ◽  
Lanzhou Institute ◽  
Related Approach ◽  
The University

Thomas R. Hoye of the University of Minnesota devised (Nature 2013, 501, 531) the reagent 2, that cyclized to a benzyne that in turn dehydrogenated the alkane 1 to the alkene 3, and 4. Abigail G. Doyle of Princeton University developed (J. Am. Chem. Soc. 2013, 135, 12990) a reagent combination for the allylic fluorination of a terminal alkene 5 to the branched product 6. Yan Zhang and Jianbo Wang of Peking University oxidized (Angew. Chem. Int. Ed. 2013, 52, 10573) the methyl group of 7 to give the nitrile 8. Hanmin Huang of the Lanzhou Institute of Chemical Physics found (Org. Lett. 2013, 15, 3370) conditions for the carbonylation of the benzylic site of 9, leading to coupling with 10 to form the amide 11. Yu Rao of Tsinghua University effected (Angew. Chem. Int. Ed. 2013, 52, 13606) the direct methoxylation of 12, to give 13. Pd-mediated methoxylation had previously been described (Chem. Sci. 2013, 4, 4187) by Bing-Feng Shi of Zhejiang University. M. Christina White of the University of Illinois, Urbana found (J. Am. Chem. Soc. 2013, 135, 14052) that with variant ligands on the Fe catalyst, the oxidation of 14 could be directed selectively to either 15 or 16. C–H bonds can also be converted to C–N bonds. Sukbok Chang of KAIST oxi­dized (J. Am. Chem. Soc. 2013, 135, 12861) the unsaturated ester 17 with 18 to form the enamide 18. Gong Chen of Pennsylvania State University cyclized (Angew. Chem. Int. Ed. 2013, 52, 11124) the amide 20 to the γ-lactam 21. Professor Shi reported (Angew. Chem. Int. Ed. 2013, 52, 13588) a related approach to β-lactams. Ethers are easily oxidized. Taking advantage of this, Yun Liang of Hunan Normal University coupled (Synthesis 2013, 45, 3137) the bromoalkyne 23 with tetrahydro­furan 22 to give 24. Guangbin Dong of the University of Texas, Austin devised (J. Am. Chem. Soc. 2013, 135, 17747) a protocol for the β-arylation of ketones, includ­ing the preparation of 27 by the coupling of 25 with 26.

Functional Group Protection

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
National Laboratory ◽  
Primary Alcohol ◽  
Selective Reduction ◽  
State University ◽  
Protecting Group ◽  
Los Alamos National Laboratory ◽  
Ru Catalyst ◽  
New Mexico State University ◽  
Peking University ◽  
The University

Zhong-Jun Li of Peking University developed (J. Org. Chem. 2011, 76, 9531) a Co catalyst for selectively replacing one benzyl protecting group of 1 with silyl. Carlo Unverzagt of Universität Bayreuth devised (Chem. Commun. 2011, 47, 10485) oxidative conditions for debenzylating the azide 3 to 4. Tadashi Katoh of Tohoku Pharmaceutical University found (Tetrahedron Lett. 2011, 52, 5395) that the dimethoxybenzyl protecting group of 5 could be selectively removed in the presence of benzyl and p-methoxybenzyl. Scott T. Phillips of Pennsylvania State University showed (J. Org. Chem. 2011, 76, 7352) that in the presence of phosphate buffer, catalytic fluoride was sufficient to desilylate 7. Philip L. Fuchs of Purdue University employed (J. Org. Chem. 2011, 76, 7834, not illustrated) the neutral Robins conditions (Tetrahedron Lett. 1992, 33, 1177) to effect a critical desilylation. Pengfei Wang of the University of Alabama at Birmingham found (J. Org. Chem. 2011, 76, 8955) that an excess of the diol 9 both oxidized the primary alcohol 10 and installed the photolabile protecting group on the product aldehyde. Hiromichi Fujioka of Osaka University showed (Angew. Chem. Int. Ed. 2011, 50, 12232) that addition of Ph3P to 12 transiently protected the aldehyde, allowing selective reduction of the ketone to the alcohol. Willi Bannwarth of Albert-Ludwigs-Universität Freiburg deprotected (Angew. Chem. Int. Ed. 2011, 50, 6175) the chelating amide of 14, leaving the usually sensitive Fmoc group in place. Bruce C. Gibb, now at Tulane University, hydrolyzed (Nature Chem. 2010, 2, 847) 16 more rapidly than the very similar 17, by selective equilibrating complexation of 16 and 17 with a cavitand. Aravamudan S. Gopalan of New Mexico State University converted (Tetrahedron Lett. 2010, 51, 6737) proline 19 to the amide ester 10 by exposure to triethyl orthoacetate. K. Rajender Reddy of the Indian Institute of Chemical Technology oxidized (Angew. Chem. Int. Ed. 2011, 50, 11748) the formamide 22 to the carbamate 23 by exposure to H2O2 in the presence of 21. James M. Boncella of the Los Alamos National Laboratory deprotected (Org. Lett. 2011, 13, 6156) 24 by exposure to visible light in the presence of a Ru catalyst.

C–O Ring Construction: The Martín and Martín Synthesis of Teurilene

2017 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Phenylboronic Acid ◽  
Gold Catalysis ◽  
State University ◽  
Max Planck ◽  
Amberlyst 15 ◽  
Colorado State University ◽  
University Of Toronto ◽  
Palladium Catalyzed ◽  
University Of Bristol ◽  
The University

Benjamin List at the Max-Planck-Institute in Mülheim reported (Angew. Chem. Int. Ed. 2013, 52, 3490) that the chiral phosphoric acid TRIP catalyzed the asymmet­ric SN2-type intramolecular etherification of 1 to produce tetrahydrofuran 2 with a selectivity factor of 82. The coupling of alkenol 3 with 4 to give the α-arylated tetra­hydropyran 5 via a method that combined gold catalysis and photoredox catalysis was disclosed (J. Am. Chem. Soc. 2013, 135, 5505) by Frank Glorius at Westfälische Wilhelms-Universität Münster. Mark Lautens at the University of Toronto reported (Org. Lett. 2013, 15, 1148) the conversion of cyclohexanedione 6 and phenylboronic acid to bicyclic ether 8 using rhodium catalysis in the presence of dienyl ligand 7. Propargylic ether 9 was found (Org. Lett. 2013, 15, 2926) by John P. Wolfe at the University of Michigan to undergo conversion to furanone 10 upon treatment with dibutylboron triflate and Hünig’s base followed by oxidation with hydrogen peroxide. Tomislav Rovis at Colorado State University demonstrated (Chem. Sci. 2013, 4, 1668) that the spirocyclic compound 13 could be prepared in enantioenriched form from 11 by a photoisomerization- coupled Stetter reaction using carbene catalyst 12. Antonio C. B. Burtoloso at the University of São Paulo reported (Org. Lett. 2013, 15, 2434) the conversion of ketone 14 to lactone 15 using samarium(II) iodide and methyl acrylate. The merger of diketone 16 and pyrone 17 in the presence of Amberlyst-15 to pro­duce (−)- tenuipyrone 18 was disclosed (Org. Lett. 2013, 15, 6) by Rongbiao Tong at the Hong Kong University of Science and Technology. Joanne E. Harvey at Victoria University of Wellington in New Zealand found (Org. Lett. 2013, 15, 2430) that tricy­clic ether 20 could be generated efficiently from dihydropyran 19 and pyrone 17 via a palladium-catalyzed double allylic alkylation cascade. Two rings and four stereocenters were generated in the construction of bicyclic ether 23 from dienol 21 and acetal 22 via a Lewis acid-mediated cascade, as reported (Org. Lett. 2013, 15, 2046) by Christine L. Willis at the University of Bristol.

Best Synthetic Methods: Reduction

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Direct Reduction ◽  
Synthetic Methods ◽  
Cancer Center ◽  
Michigan State University ◽  
State University ◽  
University Of Texas ◽  
Ru Catalyst ◽  
Reaction Matrix ◽  
National University ◽  
The University

Jaiwook Park of Pohang University of Science and Technology has developed (Org. Lett. 2007, 9, 3417) a procedure for the preparation of Pd-impregnated magnetic Fe nanoparticles. This effective hydrogenation catalyst was attracted to an external magnet and so was easily separated from the reaction matrix. Duk Keun An of Kangwon National University has found (Chem. Lett. 2007, 36, 886) that by including NaOtBu, Dibal reduction of an ester such as 3 can be made to reliably stop at the aldehyde 4. By using the easily-prepared pentaflurophenyl ester 5, Panagiota Moutevelis-Minakakis of the University of Athens was able to reduce an acid to the alcohol 6. Lionel A. Saudan of Firmenich SA, Geneva has devised (Angew. Chem. Int. Ed. 2007, 46, 7473) a Ru catalyst that will hydrogenate an ester such as 7 to the alcohol 8 without reducing an internal alkene. Norio Sakai of the Tokyo University of Science has established (J. Org. Chem. 2007, 72, 5920) what promises to be a general route to ethers 10, by direct reduction of the corresponding ester 9. Hideo Nagashima of Kyushu University has developed ( Chem. Commun. 2007, 4916) a Ru catalyst that effected selective hydrogenation of an amide 11 to the amine 12 without reducing ketones or esters. Alternatively, Jason S. Tedrow of Amgen Inc., Thousand Oaks, CA has found (J. Org. Chem. 2007, 72, 8870) that a protocol developed by Robert E. Maleczka, Jr. of Michigan State University was effective for reducing an aryl ketone 13 to the corresponding hydrocarbon 14 without reducing the amide. The stereocontrolled reductive amination of cyclic ketones such as 15 has been a continuing challenge. Shawn Cabral of Pfizer, Inc. in Groton, CT has reported (Tetrahedron Lett. 2007, 48, 7134) complementary reagent combinations, leading selectively to either 16 or 17. To control catalytic hydrogenation, it is often desirable to control the H2 supply. John S. McMurray of the University of Texas M. D. Anderson Cancer Center in Houston has shown (J. Org. Chem. 2007, 72, 6599) that Et3SiH is a convenient H2 source. Nitro alkanes add to aldehydes to give nitro alkenes such as 20.

Alkene and Alkyne Metathesis: (+)-Anamarine (Sabitha), ( ± )-Pseudotabersonine (Martin), Lactimidomycin (Fürstner)

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Indian Institute ◽  
Alkyne Metathesis ◽  
Max Planck ◽  
Ring Closing Metathesis ◽  
University Of Texas ◽  
Ru Catalyst ◽  
Cross Metathesis ◽  
University Of Zurich ◽  
Indian Institute Of Science ◽  
The University

Masato Matsugi of Meijo University showed (J. Org. Chem. 2010, 75, 7905) that over five iterations, the fluorous-tagged Ru catalyst 1b was readily recovered and reused for the cyclization of 2 to 3. Hengquan Yang of Shanxi University reported (Chem. Commun. 2010, 46, 8659) that the Hoveyda catalyst 1a encapsulated in mesoporous SBA-1 could also be reused several times. Jean-Marie Basset of KAUST Catalysis Center, Régis M. Gauvin of Université Lille, and Mostafa Taoufik of Université Lyon 1 described (Chem. Commun. 2010, 46, 8944) a W catalyst on silica that was also active for alkene metathesis. Reto Dorta of the University of Zurich, exploring several alternatives, found (J. Am. Chem. Soc. 2010, 132, 15179) that only 4c cyclized cleanly to 5. Karol Grela of the Polish Academy of Sciences showed (Synlett 2010, 2931) that 3-nitropropene (not illustrated) participated in cross-metathesis when catalyst 1c was used. Shawn K. Collins of the Université de Montré al complexed (J. Am. Chem. Soc. 2010, 132, 12790) 6 with a quinolinium salt to direct paracyclophane formation. Min Shi of the Shanghai Institute of Organic Chemistry incorporated (Org. Lett. 2010, 12, 4462) the cyclopropene 8 in cross-metathesis, to give 10. A. Srikrishna of the Indian Institute of Science (Bangalore) constructed (Synlett 2010, 3015) the cyclooctenone 12 by ring-closing metathesis. LuAnne McNulty of Butler University established (J. Org. Chem. 2010, 75, 6001) that a cyclic boronic half acid 15, prepared by ring-closing metathesis, coupled with an iodoalkene 16 to deliver the diene 17 with high geometric control. Gowravaram Sabitha of the Indian Institute of Chemical Technology, Hyderabad, en route to (+)-anamarine 21, observed (Tetrahedron Lett. 2010, 51, 5736) that the tetraacetate 18b would not participate in cross-metathesis. Fortunately, 18a , an earlier intermediate in the synthesis, worked well. Stephen F. Martin of the University of Texas prepared (Org. Lett. 2010, 12, 3622) (±)-pseudotabersonine 24 by way of a spectacular metathesis that converted 22 to 23. Ring-closing alkyne metathesis was a key step in the total synthesis of lactimidomycin 27 reported (J. Am. Chem. Soc. 2010, 132, 14064) by Alois Fürstner of the Max-Planck- Institut Mülheim.

Transition Metal-Mediated Construction of Carbocycles: Dimethyl Gloiosiphone A (Takahashi), Pasteurestin A (Mulzer), and Pentalenene (Fox)

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Transition Metal ◽  
South Florida ◽  
Health Science ◽  
Pt Catalyst ◽  
Max Planck ◽  
Au Catalyst ◽  
Ru Catalyst ◽  
National University ◽  
Rh Catalyst ◽  
The University

There continue to be new developments in transition metal- and lanthanide-mediated construction of carbocycles. Although a great deal has been published on the asymmetric cyclopropanation of styrene, relatively little had been reported for other classes of alkenes. Tae-Jeong Kim of Kyungpook National University has devised (Tetrahedron Lett. 2007, 48, 8014) a Ru catalyst for the cyclopropanation of simple α-olefins such as 1. X. Peter Zhang of the University of South Florida has developed (J. Am.Chem. Soc. 2007, 129, 12074) a Co catalyst for the cyclopropanation of alkenes such as 5 having electron-withdrawing groups. Alexandre Alexakis of the Université de Genève has reported(Angew. Chem. Int. Ed. 2007, 46, 7462) simple monophosphine ligands that enabled enantioselective conjugate addition to prochiral enones, even difficult substrates such as 8. Seunghoon Shin of Hanyang University has found (Organic Lett. 2007, 9, 3539) an Au catalyst that effected the diastereoselective cyclization of 10 to the cyclohexene 11, and Radomir N. Saicic of the University of Belgrade has carried out (Organic Lett. 2007, 9, 5063), via transient enamine formation, the diastereoselective cyclization of 12 to the cyclohexane 13. Alois Fürstner of the Max-Planck- Institut, Mülheim has devised (J. Am. Chem. Soc. 2007, 129, 14836) a Rh catalyst that cyclized the aldehyde 14 to the cycloheptenone 15. Some of the most exciting investigations reported in recent months have been directed toward the direct diastereo- and enantioselective preparation of polycarbocyclic products. Rai-Shung Liu of National Tsing-Hua University has extended (J. Org. Chem. 2007, 72, 567) the intramolecular Pauson-Khand cyclization to the epoxy enyne 16, leading to the 5-5 product 17. Michel R. Gagné of the University of North Carolina has devised (J. Am. Chem. Soc. 2007, 129, 11880) a Pt catalyst that smoothly cyclized the polyene 18 to the 6-6 product 19. Yoshihiro Sato of Hokkaido University and Miwako Mori of the Health Science University of Hokkaido have described (J. Am. Chem. Soc. 2007, 129, 7730) a Ru catalyst for the cyclization of 20 to the 5-6-5 product 21. Each of these processes proceeded with high diastereocontrol.

Other Methods for Carbocyclic Construction: The Porco Synthesis of (-)-Hyperibone K

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Oxidative Cyclization ◽  
Florida State University ◽  
State University ◽  
Colorado State University ◽  
Intramolecular Alkylation ◽  
University Of Wisconsin ◽  
Tokyo Institute ◽  
Institute Of Technology ◽  
University Of Bristol ◽  
The University

Varinder K. Aggarwal of the University of Bristol described (Angew. Chem. Int. Ed. 2010, 49, 6673) the conversion of the Sharpless-derived epoxide 1 into the cyclopropane 2. Christopher D. Bray of Queen Mary University of London established (Chem. Commun. 2010, 46, 5867) that the related conversion of 3 to 5 proceeded with high diastereocontrol. Javier Read de Alaniz of the University of California, Santa Barbara, extended (Angew. Chem. Int. Ed. 2010, 49, 9484) the Piancatelli rearrangement of a furyl carbinol 6 to allow inclusion of an amine 7, to give 8. Issa Yavari of Tarbiat Modares University described (Synlett 2010, 2293) the dimerization of 9 with an amine to give 10. Jeremy E. Wulff of the University of Victoria condensed (J. Org. Chem. 2010, 75, 6312) the dienone 11 with the commercial butadiene sulfone 12 to give the highly substituted cyclopentane 13. Robert M. Williams of Colorado State University showed (Tetrahedron Lett. 2010, 51, 6557) that the condensation of 14 with formaldehyde delivered the cyclopentanone 15 with high diastereocontrol. D. Srinivasa Reddy of Advinus Therapeutics devised (Tetrahedron Lett. 2010, 51, 5291) conditions for the tandem conjugate addition/intramolecular alkylation conversion of 16 to 17. Marie E. Krafft of Florida State University reported (Synlett 2010, 2583) a related intramolecular alkylation protocol. Takao Ikariya of the Tokyo Institute of Technology effected (J. Am. Chem. Soc. 2010, 132, 11414) the enantioselective Ru-mediated hydrogenation of bicyclic imides such as 18. This transformation worked equally well for three-, four-, five-, six-, and seven-membered rings. Stefan France of the Georgia Institute of Technology developed (Org. Lett. 2010, 12, 5684) a catalytic protocol for the homo-Nazarov rearrangement of the doubly activated cyclopropane 20 to the cyclohexanone 21. Richard P. Hsung of the University of Wisconsin effected (Org. Lett. 2010, 12, 5768) the highly diastereoselective rearrangement of the triene 22 to the cyclohexadiene 23. Strategies for polycyclic construction are also important. Sylvain Canesi of the Université de Québec devised (Org. Lett. 2010, 12, 4368) the oxidative cyclization of 24 to 25.

Substituted Benzenes: The Saikawa/Nakata Synthesis of Kendomycin

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Alkyl Iodide ◽  
Benzene Derivative ◽  
State University ◽  
One Pot ◽  
Aryl Iodide ◽  
Peking University ◽  
Cu Catalyst ◽  
San Diego State University ◽  
University Of Massachusetts ◽  
The University

Jianbo Wang of Peking University described (Angew. Chem. Int. Ed. 2010, 49, 2028) the Au-promoted bromination of a benzene derivative such as 1 with N-bromosuccinimide. In a one-pot procedure, addition of a Cu catalyst followed by microwave heating delivered the aminated product 2. Jian-Ping Zou of Suzhou University and Wei Zhang of the University of Massachusetts, Boston, observed (Tetrahedron Lett. 2010, 51, 2639) that the phosphonylation of an arene 3 proceeded with substantial ortho selectivity. Yonghong Gu of the University of Science and Technology, Hefei, showed (Tetrahedron Lett. 2010, 51, 192) that an arylpropanoic acid 6 could be ortho hydroxylated with PIFA to give 7. Louis Fensterbank, Max Malacria, and Emmanuel Lacôte of UMPC Paris found (Angew. Chem. Int. Ed. 2010, 49, 2178) that a benzoic acid could be ortho aminated by way of the cyano amide 8. Daniel J. Weix of the University of Rochester developed (J. Am. Chem. Soc. 2010, 132, 920) a protocol for coupling an aryl iodide 10 with an alkyl iodide 11 to give 12. Professor Wang devised (Angew. Chem. Int. Ed. 2010, 49, 1139) a mechanistically intriguing alkyl carbonylation of an iodobenzene 10. This is presumably proceeding by way of the intermediate diazo alkane. Usually, benzonitriles are prepared by cyanation of the halo aromatic. Hideo Togo of Chiba University established (Synlett 2010, 1067) a protocol for the direct electrophilic cyanation of an electron-rich aromatic 15. Thomas E. Cole of San Diego State University observed (Tetrahedron Lett. 2010, 51, 3033) that an alkyl dimethyl borane, readily prepared by hydroboration of the alkene with BCl3 and Et3 SiH, reacted with benzoquinone 17 to give 18. Presumably this transformation could also be applied to substituted benzoquinones. When a highly substituted benzene derivative is needed, it is sometimes more economical to construct the aromatic ring. Joseph P. A. Harrity of the University of Sheffield and Gerhard Hilt of Philipps-Universität Marburg showed (J. Org. Chem. 2010, 75, 3893) that the Co-catalyzed Diels-Alder cyloaddition of alkynyl borinate 21 with a diene 20 proceeded with high regiocontrol, to give, after oxidation, the aryl borinate 22.

Functionalization and Homologation of C-H Bonds

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Crop Protection ◽  
Oxidative Cyclization ◽  
South Florida ◽  
State University ◽  
Ru Catalyst ◽  
University Of Oklahoma ◽  
Princeton University ◽  
La Jolla ◽  
The University ◽  
Technological University

Justin Du Bois of Stanford University developed (J. Am. Chem. Soc. 2010, 132, 10202) a Ru catalyst for the stereoretentive hydroxylation of 1 to 2. John T. Groves of Princeton University effected (J. Am. Chem. Soc. 2010, 132, 12847) equatorial chlorination of the test substrate 3. Kenneth M. Nicholas of the University of Oklahoma found (J. Org. Chem. 2010, 75, 7644) that I2 catalyzed the amination of 5. Thorsten Bach of the Technische Universität München established (Org. Lett. 2010, 12, 3690) that the amination of 7 proceeded with significant diastereoselectivity. Phil S. Baran of Scripps/La Jolla compiled (Synlett 2010, 1733) an overview of the development of C-H oxidation. Tethering can improve the selectivity of C-H functionalization. X. Peter Zhang of the University of South Florida devised (Angew. Chem. Int. Ed. 2010, 49, 10192) a Co catalyst for the cyclization of 9 to 10. Teck-Peng Loh of Nanyang Technological University established (Angew. Chem. Int. Ed. 2010, 49, 8417) conditions for the oxidation of 11 to 12. Jin-Quan Yu, also of Scripps/La Jolla, effected (J. Am. Chem. Soc. 2010, 132, 17378) carbonylation of methyl C-H of 13 to give 14. Sunggak Kim, now also at Nanyang Technological University, established (Synlett 2010, 1647) conditions for the free-radical homologation of 15 to 17. Gong Chen of Pennsylvania State University extended (Org. Lett. 2010, 12, 3414) his work on remote Pd-mediated activation by cyclizing 18 to 19. Many schemes have been developed in recent years for the oxidation of substrates to reactive electrophiles. Gonghua Song of the East China University of Science and Technology and Chao-Jun Li of McGill University reported (Synlett 2010, 2002) Fe nanoparticles for the oxidative coupling of 20 with 21. Zhi-Zhen Huang of Nanjing University found (Org. Lett. 2010, 12, 5214) that protonated pyrrolidine 25 was important for mediating the site-selective coupling of 24 with 23. Y. Venkateswarlu of the Indian Institute of Chemical Technology, Hyderabad, was even able (Tetrahedron Lett. 2010, 51, 4898) to effect coupling with a cyclic alkene 28. AB3217-A 32, isolated in 1992, was shown to have marked activity against two spotted spider mites. Christopher R. A. Godfrey of Syngenta Crop Protection, Münchwilen, prepared (Synlett 2010, 2721) 32 from commercial anisomycin 30a. The key step in the synthesis was the oxidative cyclization of 30b to 31.

C–O Ring Formation

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
State University ◽  
Wayne State University ◽  
Northwestern University ◽  
Iminium Ion ◽  
Peking University ◽  
Complete Reversal ◽  
Dyotropic Rearrangement ◽  
The University

A reductive radical cyclization of tetrahydropyran 1 to form bicycle 2 using iron(II) chloride in the presence of NaBH4 was reported (Angew. Chem. Int. Ed. 2012, 51, 6942) by Louis Fensterbank and Cyril Ollivier at the University of Paris and Anny Jutand at the Ecole Normale Supérieure. The enantioselective conversion of tetrahydrofuran 3 to spirocycle 5 via iminium ion-catalyzed hydride transfer/cyclization was developed (Angew. Chem. Int. Ed. 2012, 51, 8811) by Yong-Qiang Tu at Lanzhou University. Daniel Romo at Texas A&M University showed (J. Am. Chem. Soc. 2012, 134, 13348) that enantioenriched tricyclic β-lactone 8 could be readily prepared via dyotropic rearrangement of the diketoacid 6 under catalysis by chiral Lewis base 7. A dyotropic rearrangement was also utilized (Angew. Chem. Int. Ed. 2012, 51, 6984) by Zhen Yang at Peking University, Tuoping Luo at H3 Biomedicine in Cambridge, MA, and Yefeng Tang at Tsinghua University for the conversion of 9 to the bicyclic lactone 10. In terms of the enantioselective synthesis of β-lactones, Karl Scheidt at Northwestern University found that NHC catalyst 12 effects (Angew. Chem. Int. Ed. 2012, 51, 7309) the dynamic kinetic resolution of aldehyde 11 to furnish the lactone 13 with very high ee. Meanwhile, Xiaomeng Feng at Sichuan University has developed (J. Am Chem. Soc. 2012, 134, 17023) a rare example of an enantioselective Baeyer-Villiger oxidation of 4-alkyl cyclohexanones such as 14. The diastereoselective preparation of tetrahydropyran 18 by Lewis acid-promoted cyclization of cyclopropane 17 was accomplished (Org. Lett. 2012, 14, 6258) by Jin Kun Cha at Wayne State University. Stephen J. Connon at the University of Dublin reported (Chem. Commun. 2012, 48, 6502) the formal cycloaddition of aryl succinic anhydrides such as 18 with aldehydes to produce γ-butyrolactones, including 20, in high ee. The stereodivergent cyclization of 21 via desilylation-induced heteroconjugate addition to produce the complex tetrahydropyran 22 was discovered (Org. Lett. 2012, 14, 5550) by Paul A. Clarke at the University of York. Remarkably, while TFA produced a 13:1 diastereomeric ratio in favor of the cis diastereomer 22, the use of TBAF resulted in complete reversal of diastereoselectivity.

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