Organocatalysis of Carbocyclic Construction: The MacMillan Synthesis of (+)-Frondosin B

Organic Synthesis ◽

10.1093/oso/9780199965724.003.0071 ◽

2013 ◽

Author(s):

Douglass F. Taber

Keyword(s):

Organic Chemistry ◽

Claisen Rearrangement ◽

Kinetic Resolution ◽

Membered Ring ◽

Max Planck ◽

Princeton University ◽

Michael Condensation ◽

Carbocyclic Rings ◽

Robinson Annulation ◽

Technological University

One of the more powerful applications of organocatalysis has been the enantioselective transformation of preformed prochiral rings. In the five-membered ring series, Nobuyuki Mase of Shizuoka University effected (Synlett 2010, 2340) enantioselective addition of malonate to cyclopentenone 1, and Eric N. Jacobsen of Harvard University devised (Angew. Chem. Int. Ed. 2010, 49, 9753) a guanidinium catalyst for the Claisen rearrangement of 4 to 5. Jacek Mlynarski of Jagiellonian University accomplished (Tetrahedron Lett. 2010, 51, 4088) the enantioselective hydroxymethylation of 6. This worked equally well for cyclopentanone and cycloheptanone. The dynamic kinetic resolution/reductive amination of 8 described (Angew. Chem. Int. Ed. 2010, 49, 4612) by Benjamin List of the Max-Planck-Institut Mülheim worked best with cyclohexanones such as 8. Organocatalysts can also be effective for the construction of carbocyclic rings. Teck-Peng Loh of Nanyang Technological University found (Chem. Sci. 2010, 1, 739) a commercial phosphine catalyst that efficiently mediated the condensation of 10 with 11. David W. C. MacMillan of Princeton University used (J. Am. Chem. Soc. 2010, 132, 10015) a SOMO catalyst to combine 13 with 14 to make 15. Dawei Ma of the Shanghai Institute of Organic Chemistry employed (Org. Lett. 2010, 12, 3634) the Hayashi catalyst in the double Michael condensation of 16 with 17. Daniel Romo of Texas A&M University showed (Org. Lett. 2010, 12, 3764) that the appropriate organocatalyst could direct 19 to either diastereomer of the β-lactone 20. Professor Romo also reported (Angew. Chem. Int. Ed. 2010, 49, 9479) the desymmetrization of 2-alkyl cyclohexane-1,3-diones using a similar approach. In the six-membered ring series, José Alemán and José Luis García Ruano of the Universidad Autónoma de Madrid carried out (Eur. J. Org. Chem. 2010, 4482) Robinson annulation of 17 with 21. Ying-Chun Chen of Sichuan University, again using the Hayashi catalyst, reported (Angew. Chem. Int. Ed. 2010, 49, 6418) the addition of 17 to 23 to give 24. In another elegant application of visible light–mediated organocatalysis, Professor MacMillan described (Chem. Sci. 2010, 1, 37) the addition of the commercial boronic acid 25 to 17.

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Enantioselective Organocatalyzed Construction of Carbocyclic Rings

Organic Synthesis ◽

10.1093/oso/9780199764549.003.0072 ◽

2011 ◽

Author(s):

Douglass Taber

Keyword(s):

Michael Addition ◽

Max Planck ◽

Enantiomerically Pure ◽

Single Diastereomer ◽

Stereogenic Centers ◽

Aldol Cyclization ◽

National University ◽

Carbocyclic Rings ◽

Asymmetric Transformation ◽

Technological University

One of the most practical ways to construct enantiomerically-enriched carbocyclic systems is to effect asymmetric transformation of preformed prochiral rings. Choon-Hong Tan of the National University of Singapore observed (Chem. Commun. 2008, 5526) that allylic halides such as 1 coupled with malonates such as 2 to give the α-methylene ketone 3 in high ee. Xinmiao Liang of the Dalian Institute of Chemical Physics and Jinxing Ye of the East China University of Science and Technology reported (Chem. Commun. 2008, 3302) that nitromethane 5 could be added to enones such as 4 to construct cyclic quaternary stereogenic centers such as that of 6. The addition of the cyclohexanone 7 to the acceptor 8 described (Chem. Commun. 2008, 6315) by Yixin Lu, also of the National University of Singapore led to the creation of two new cyclic stereogenic centers. Polycarbocyclic prochiral rings are also of interest. Teck-Peng Loh of Nanyang Technological University devised (Tetrahedron Lett. 2008, 49, 5389) the steroid AB donor 10, that added to crotonaldehyde 1 to give the single enantiomerically-pure diastereomer 12. Nitro alkenes are excellent Michael acceptors. Dieter Enders of RWTH Aachen took advantage of this (Angew. Chem. Int. Ed. 2008, 47, 7539) in developing the addition of aldehydes such as 14 to the nitroalkene 13. Intramolecular alkylation ensued, to deliver the product 15 as a single diastereomer. Guofu Zhong, also of Nanyang Technological University, established (Organic Lett. 2008, 10, 3425; Organic Lett. 2008, 10, 3489) an approach to cyclopentane construction based on the Michael addition of β-ketoesters such as 16 and 19 to nitroalkenes such as 17 and 20. Intramolecular nitro aldol (Henry) addition led to 18, while an intramolecular Michael addition delivered 21. Damien Bonne and Jean Rodriguez of Aix-Marseille Université employed (Organic Lett. 2008, 10, 5409) intramolecular dipolar cycloaddition to convert the initial adduct between 22 and 23 to the cyclopentane 24. They also prepared cyclohexane derivatives using this approach. The diketone 25 is prochiral. Benjamin List of the Max-Planck Institut, Mülheim devised (Angew. Chem. Int. Ed. 2008, 47, 7656) an organocatalyst that mediated the intramolecular aldol cyclization of 25 to 26 in high ee.

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Seven-Membered Ring Formation through a Robinson Annulation

Category 6, Compounds with All-Carbon Functions ◽

10.1055/sos-sd-045-01169 ◽

2010 ◽

pp. 1

Author(s):

K. Abou-Hadeed ◽

H.-J. Hansen

Keyword(s):

Membered Ring ◽

Ring Formation ◽

Robinson Annulation

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C-O Ring Containing Natural Products: Paeonilactone B (Taylor), Deoxymonate B (de la Pradilla), Sanguiin H-5 (Spring), Solandelactone A (White), Spirastrellolide A (Paterson)

Organic Synthesis ◽

10.1093/oso/9780199764549.003.0050 ◽

2011 ◽

Author(s):

Douglass Taber

Keyword(s):

Oxidative Coupling ◽

Claisen Rearrangement ◽

Cyclic Carbonate ◽

Membered Ring ◽

State University ◽

Enantiomerically Pure ◽

University Of Cambridge ◽

Spirastrellolide A ◽

The University ◽

Oregon State University

Richard J. K. Taylor of the University of York has developed (Angew. Chem. Int. Ed. 2008, 47, 1935) the diasteroselective intramolecular Michael cyclization of phosphonates such as 2. Quenching of the cyclized product with paraformaldehyde delivered ( + )-Paeonilactone B 3. Roberto Fernández de la Pradilla of the CSIC, Madrid established (Tetrahedron Lett. 2008, 49, 4167) the diastereoselective intramolecular hetero Michael addition of alcohols to enantiomerically-pure acyclic sulfoxides such as 4 to give the allylic sulfoxide 5. Mislow-Evans rearrangement converted 5 into 6, the enantiomerically-pure core of Ethyl Deoxymonate B 7. The ellagitannins, represented by 10, are single atropisomers around the biphenyl linkage. David R. Spring of the University of Cambridge found (Organic Lett. 2008, 10, 2593) that the chiral constraint of the carbohydrate backbone of 9 directed the absolute sense of the oxidative coupling of the mixed cuprate derived from 9, leading to Sanguiin H-5 10 with high diastereomeric control. A key challenge in the synthesis of the solandelactones, exemplified by 14, is the stereocontrolled construction of the unsaturated eight-membered ring lactone. James D. White of Oregon State University found (J. Org. Chem. 2008, 73, 4139) an elegant solution to this problem, by exposure of the cyclic carbonate 11 to the Petasis reagent, to give 12. Subsequent Claisen rearrangement delivered the eight-membered ring lactone, at the same time installing the ring alkene of Solandelactone E 14. AD-mix usually proceeds with only modest enantiocontrol with terminal alkenes. None the less, Ian Paterson, also of the University of Cambridge, observed (Angew. Chem. Int. Ed. 2008, 47, 3016, Angew. Chem. Int. Ed. 2008, 47, 3021) that bis-dihydroxylation of the diene 17 proceeded to give, after acid-mediated cyclization, the bis-spiro ketal core 18 of Spirastrellolide A Methyl Ester 19 with high diastereocontrol.

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Functionalization and Homologation of C-H Bonds

Organic Synthesis ◽

10.1093/oso/9780199965724.003.0020 ◽

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.

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Enantioselective Synthesis of Alkylated Centers: The Fukuyama Synthesis of (–)-Histrionicotoxin

Organic Synthesis ◽

10.1093/oso/9780190200794.003.0039 ◽

2015 ◽

Author(s):

Douglass F. Taber

Keyword(s):

Indian Institute ◽

Enantioselective Synthesis ◽

Max Planck ◽

Dimethyl Malonate ◽

Co Catalyst ◽

Cu Catalyst ◽

Enantioselective Addition ◽

Institute Of Technology ◽

Enantioselective Alkylation ◽

Technological University

Vinod K. Singh of the Indian Institute of Technology, Kanpur optimized (Org. Lett. 2011, 13, 6520) an organocatalyst for the enantioselective addition of thiophenol to an imide 1 to give 2 in high ee. Amir H. Hoveyda of Boston College developed (Angew. Chem. Int. Ed. 2011, 50, 7079) a Cu catalyst for the preparation of 4 by the enantioselective hydroboration of a 1,1-disubstituted alkene 3. Yong-Qiang Tu of Lanzhou University effected (Chem. Sci. 2011, 2, 1839) enantioselective bromination of the prochiral 5 to give the bromoketone 6. Song Ye of the Institute of Chemistry, Beijing established (Chem. Commun. 2011, 47, 8388) the alkylated quaternary center of the dimer 8, by condensing a ketene 7 with CS2. Li Deng of Brandeis University added (Angew. Chem. Int. Ed. 2011, 50, 10565) cyanide in a conjugate sense to an acyl imidazole 9 to give 11. Pier Giorgio Cozzi of the Università di Bologna prepared (Angew. Chem. Int. Ed. 2011, 50, 7842) the thioacetal 14 by condensing 13 with an aldehyde 12, followed by reduction. Takahiro Nishimura and Tamio Hayashi of Kyoto University devised (Chem. Commun. 2011, 47, 10142) a Co catalyst for the enantioselective addition of a silyl alkyne 16 to an enone 15 to give the alkynyl ketone 17. Ping Tian and Guo-Qiang Lin of the Shanghai Institute of Organic Chemistry described (Tetrahedron 2011, 67, 10186) improved catalysts for the enantioselective conjugate addition of dimethyl malonate 19 to the nitroalkene 18, to give 20. Keiji Maruoka, also of Kyoto University, established (Chem. Sci. 2011, 2, 2311) conditions for the enantioselective addition of an aldehyde 21 to the acceptor 22 to give, after reduction, an alcohol 23 that could readily be cyclized to the lactone. Jianrong (Steve) Zhou of Nanyang Technological University prepared (J. Am. Chem. Soc. 2011, 133, 15882) the ester 26 by arylation, under Pd catalysis, of a ketene silyl acetal 24 with the triflate 25. Benjamin List of the Max-Planck-Institut, Mülheim employed (Angew. Chem. Int. Ed. 2011, 50, 9471) a system of three catalysts to effect the enantioselective alkylation of an aldehyde 27 with the allyic alcohol 28 to give 29.

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Heteroaromatics: The Zhou/Li Synthesis of Goniomitine

Organic Synthesis ◽

10.1093/oso/9780190646165.003.0067 ◽

2017 ◽

Author(s):

Douglass F. Taber

Keyword(s):

Organic Chemistry ◽

Oxidative Cyclization ◽

Silyl Ether ◽

Keto Ester ◽

Transfer Protein ◽

Shanghai Institute ◽

Lanzhou Institute ◽

Institute Of Technology ◽

The University ◽

Technological University

Xin-Yan Wu of East China University of Science and Technology and Jun Yang of the Shanghai Institute of Organic Chemistry added (Tetrahedron Lett. 2014, 55, 4071) the Grignard reagent 1 to propargyl alcohol 2 to give an intermediate that could be borylated, then coupled under Pd catalysis with an anhydride, leading to the furan 3. Fuwei Li of the Lanzhou Institute of Chemical Physics constructed (Org. Lett. 2014, 16, 5992) the furan 6 by oxidizing the keto ester 4 in the presence of the enamide 5. Yuanhong Liu of the Shanghai Institute of Organic Chemistry prepared (Angew. Chem. Int. Ed. 2014, 53, 11596) the pyrrole 9 by reducing the azadiene 7 with the Negishi reagent, then adding the nitrile 8. Yefeng Tang of Tsinghua University found (Tetrahedron Lett. 2014, 55, 6455) that the Rh carbene derived from 11 could be added to an enol silyl ether 10 to give the pyrrole 12. Pazhamalai Anbarasan of the Indian Institute of Technology Madras reported (J. Org. Chem. 2014, 79, 8428) related results. Zheng Huang of the Shanghai Institute of Organic Chemistry established (Angew. Chem. Int. Ed. 2014, 53, 1390) a connection between substituted piperidines and pyridines by dehydrogenating 13 to 15, with 14 as the acceptor. Joseph P. A. Harrity of the University of Sheffield conceived (Chem. Eur. J. 2014, 20, 12889) the cascade assembly of the pyridine 18 by cycloaddition of 16 with 17 followed by Pd-catalyzed coupling. Teck-Peng Loh of Nanyang Technological University converted (Org. Lett. 2014, 16, 3432) the keto ester 19 into the azirine, then eliminated it to form an azatriene that cyclized to the pyridine 20. En route to a cholesteryl ester transfer protein inhibitor, Zhengxu S. Han of Boehringer Ingelheim combined (Org. Lett. 2014, 16, 4142) 21 with 22 to give an intermediate that could be oxidized to 23. Magnus Rueping of RWTH Aachen used (Angew. Chem. Int. Ed. 2014, 53, 13264) an Ir photoredox catalyst in conjunction with a Pd catalyst to cyclize the enamine 24 to the indole 25. Yingming Yao and Yingsheng Zhao of Soochow University effected (Angew. Chem. Int. Ed. 2014, 53, 9884) oxidative cyclization of 26 to 27.

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