Establishing Arrays of Stereogenic Centers: The Sato/Chida Synthesis of (-)-Kainic Acid

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Catalyst System ◽  
Allylic Alcohol ◽  
University Of Pennsylvania ◽  
Ni Catalyst ◽  
Max Planck ◽  
Stereogenic Centers ◽  
University College London ◽  
Enantioselective Addition ◽  
La Jolla ◽  
The University

Benjamin List of the Max-Planck-Institut, Mülheim, devised (J. Am. Chem. Soc. 2010, 132, 10227) a catalyst system for the stereocontrolled epoxidation of a trisubstituted alkenyl aldehyde 1. Takashi Ooi of Nagoya University effected (Angew. Chem. Int. Ed. 2010, 49, 7562; see also Org. Lett. 2010, 12, 4070) enantioselective Henry addition to an alkynyl aldehyde 3. Madeleine M. Joullié of the University of Pennsylvania showed (Org. Lett. 2010, 12, 4244) that an amine 7 added selectively to an alkynyl aziridine 6. Yutaka Ukaji and Katsuhiko Inomata of Kanazawa University developed (Chem. Lett. 2010, 39, 1036) the enantioselective dipolar cycloaddition of 9 with 10. K. C. Nicolaou of Scripps/La Jolla observed (Angew. Chem. Int. Ed. 2010, 49, 5875; see also J. Org. Chem. 2010, 75, 8658) that the allylic alcohol from enantioselective reduction of 12 could be hydrogenated with high diastereocontrol. Masamichi Ogasawara and Tamotsu Takahashi of Hokkaido University added (Org. Lett. 2010, 12, 5736) the allene 14 to the acetal 15 with substantial stereocontrol. Helen C. Hailes of University College London investigated (Chem. Comm. 2010, 46, 7608) the enzyme-mediated addition of 18 to racemic 17. Dawei Ma of the Shanghai Institute of Organic Chemistry, in the course of a synthesis of oseltamivir (Tamiflu), accomplished (Angew. Chem. Int. Ed. 2010, 49, 4656) the enantioselective addition of 21 to 20. Shigeki Matsunaga of the University of Tokyo and Masakatsu Shibasaki of the Institute of Microbial Chemistry developed (Org. Lett. 2010, 12, 3246) a Ni catalyst for the enantioselective addition of 23 to 24. Juthanat Kaeobamrung and Jeffrey W. Bode of ETH-Zurich and Marisa C. Kozlowski of the University of Pennsylvania devised (Proc. Natl. Acad. Sci. 2010, 107, 20661) an organocatalyst for the enantioselective addition of 27 to 26. Yihua Zhang of China Pharmaceutical University and Professor Ma effected (Tetrahedron Lett. 2010, 51, 3827) the related addition of 27 to 29. There have been scattered reports on the stereochemical course of the coupling of cyclic secondary organometallics. In a detailed study, Paul Knochel of Ludwig-Maximilians- Universität München showed (Nat. Chem. 2020, 2, 125) that equatorial bond formation dominated, exemplified by the conversion of 31 to 33.

Practical Enantioselective Construction of Arrays of Stereogenic Centers: The Jørgensen Synthesis of the Autoregulator IM-2

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
University Of Pennsylvania ◽  
Gel Chromatography ◽  
Max Planck ◽  
West Virginia University ◽  
Clemson University ◽  
Stereogenic Centers ◽  
Cu Catalyst ◽  
Enantioselective Epoxidation ◽  
Silica Gel Chromatography ◽  
The University

Armando Córdova of Stockholm University found (Angew. Chem. Int. Ed. 2008, 47, 8468) that the enantiomerically-enriched diastereomers from aminosulfenylation of 1 were readily separable by silica gel chromatography. Benjamin List of the Max-Planck-Institut, Mülheim developed (Angew. Chem. Int. Ed. 2008, 47, 8112) what appears to be a general protocol for the enantioselective epoxidation of enones such as 4. Paolo Melchiorre of the Università di Bologna devised (Angew. Chem. Int. Ed. 2008, 47 , 8703) a related protocol for the enantioselective aziridination of enones. Xue-Long Hue of the Shanghai Institute of Organic Chemistry and Yun-Dong Wu of the Hong Kong University of Science and Technology optimized (J. Am. Chem. Soc. 2008, 130 , 14362) a Cu catalyst for enantioselective Mannich homologation of imines such as 6. Guofu Zhong of Nanyang Technological University, Singapore established (Angew. Chem. Int. Ed. 2008, 47, 10187; Organic Lett. 2008 , 10 , 4585) that enantioselective α-aminoxylation of an ω-alkenyl aldehyde such as 9 could lead to defined arrays of stereogenic centers. George A. O’Doherty of West Virginia University devised (Organic Lett. 2008, 10, 3149) a protocol for the enantioselective hydration of 12 to 13 . René Peters, now at the University of Stuttgart, designed (Angew. Chem. Int. Ed. 2008, 47, 5461) an Al catalyst for the enantioselective combination of an acyl bromide 15 with an aldehyde 14 to deliver the β–lactone 16. Hajime Ito and Masaya Sawamura of Hokkaido University established (J. Am. Chem. Soc. 2008, 130, 15774) that the allenyl borane from 17 added to aldehydes such as 18 with high ee. Keiji Maruoka of Kyoto University developed (Tetrahedron Lett. 2008, 49, 5369) an organocatalyst for the Mannich homologation of an aldehyde such as 20 to 21. R. Karl Dieter of Clemson University showed (Organic Lett. 2008, 10, 2087) that 23, readily prepared in high ee, could be displaced sequentially with two different Grignard reagents, to give 24. Jeffrey W. Bode, now at the University of Pennsylvania, found (Organic Lett. 2008, 10, 3817) that bisulfite adducts such as 25 served well for the addition of unstable chloroaldehydes to 26 to give 27.

Substituted Benzenes: The Garg Synthesis of Tubingensin A

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
University Of Pennsylvania ◽  
Ni Catalyst ◽  
Indiana University ◽  
Aryl Iodide ◽  
Shanghai Institute ◽  
Peking University ◽  
Normal University ◽  
La Jolla ◽  
The University

John F. Hartwig of the University of California, Berkeley devised (Science 2014, 343, 853) conditions for the regioselective silylation of an arene 1 to give 2. The silyl group can directly be converted, inter alia, to halo, amino, alkyl, or hydroxyl. Jin-Quan Yu of Scripps La Jolla effected (Angew. Chem. Int. Ed. 2014, 53, 2683) regioselective alkenylation of the arene 3 with 4 to give 5. Wei-Liang Duan of the Shanghai Institute of Organic Chemistry described (Org. Lett. 2014, 16, 500) a related alkenyl­ation protocol. Deping Wang of Henyang Normal University developed (Eur. J. Org. Chem. 2014, 315) inexpensive conditions for the conversion of an aryl bromide 6 to the corre­sponding phenol 7. Mamoru Tobisu and Naoto Chatani of Osaka University used (J. Am. Chem. Soc. 2014, 136, 5587) a Ni catalyst to convert the lactam 8 to the aryl boro­nate 9. Patrick J. Walsh of the University of Pennsylvania found (Adv. Synth. Catal. 2014, 356, 165) conditions for the clean monoarylation of the amide 11 with 10 to give 12. In an application of the Catellani approach, Zhi- Yuan Chen of Jiangxi Normal University coupled (Chem. Eur. J. 2014, 20, 4237) the aryl iodide 13 with 14 to give the amino ester 15. Frederic Fabis of the Université de Caen-Basse-Normandie used (Chem. Eur. J. 2014, 20, 7507) Pd to catalyze the ortho halogenation (and alkoxylation) of the N-sulfonylamide 16 to give 17. Wen Wan of Shanghai University and Jian Hao of Shanghai University and the Shanghai Institute of Organic Chemistry effected (Chem. Commun. 2014, 50, 5733) ortho azidination of the aniline 18 with 19, leading to 20. Jianbo Wang of Peking University found (Angew. Chem. Int. Ed. 2014, 53, 1364) that the N-aryloxy amide 21 could be combined with the α-diazo ester 22 to give the ortho-alkenyl phenol 23. Silas P. Cook of Indiana University uncovered (Org. Lett. 2014, 16, 2026) remarkably simple conditions for the enantiospecific cyclization of 24 (65% ee) to 25 (63% ee). The development of arynes as reactive intermediates continues unabated. Xiaoming Zeng of Xi’an Jiaotong University developed (Org. Lett. 2014, 16, 314) the reagent 27 for the bis-functionalization of the aryne derived from 26.

Alkene and Alkyne Metathesis: Phaseolinic Acid (Selvakumar), Methyl 7-Dihydro-trioxacarcinoside B (Koert), Arglabin (Reiser) and Amphidinolide V (Fürstner)

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Organic Synthesis ◽  
Second Generation ◽  
Secondary Alcohol ◽  
Allylic Alcohol ◽  
Alkyne Metathesis ◽  
Max Planck ◽  
Ring Closing Metathesis ◽  
Relative Configuration ◽  
Stereogenic Centers ◽  
Ru Complexes

As N. Selvakumar of Dr. Reddy’s Laboratories, Ltd., Hyderabad approached (Tetrahedron Lett. 2007, 48, 2021) the synthesis of phaseolinic acid 6, there was some concern about the projected cyclization of 2 to 3, as this would involve the coupling of two electron-deficient alkenes. In fact, the Ru-mediated ring-closing metathesis proceeded efficiently. The product unsaturated lactone 3 could be reduced selectively to either the trans product 4 or the cis product 5. There has been relatively little work on the synthesis of the higher branched sugars, such as the octalose 13, a component of several natural products. The synthesis of 13 (Organic Lett. 2007, 9, 4777) by Ulrich Koert of the Philipps-University Marburg also began with a Baylis-Hillman product, the easily-resolved secondary alcohol 8. As had been observed in other contexts, cyclization of the protected allylic alcohol 9a failed, but cyclization of the free alcohol 9b proceeded smoothly. V-directed epoxidation then set the relative configuration of the stereogenic centers on the ring. Ring-closing metathesis to construct tetrasubstituted alkenes has been a challenge, and specially-designed Ru complexes have been put forward specifically for this transformation. Oliver Reiser of the Universität Regensburg was pleased to observe (Angew. Chem. Int. Ed. 2007, 46, 6361) that the second-generation Grubbs catalyst itself worked well for the cyclization of 17 to 18. Again in this synthesis, catalytic V was used to direct the relative configuration of the epoxide. Intramolecular alkyne metathesis is now well-established as a robust and useful method for organic synthesis. It was also known that Ru-mediated metathesis of an alkyne with ethylene could lead to the diene. The question facing (Angew. Chem. Int. Ed . 2007, 46, 5545) Alois Fürstner of the Max-Planck-Institut, Mülheim was whether these transformations could be carried out on the very delicate epoxy alkene 21. In fact, the transformations of 21 to 22 and of 22 to 23 proceeded well, setting the stage for the total synthesis of Amphidinolide V 25.

Best Synthetic Methods: C-C Bond Construction

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Allylic Alcohol ◽  
Synthetic Methods ◽  
Grignard Reagents ◽  
Ni Catalyst ◽  
University Of Texas ◽  
University Of British Columbia ◽  
Terminal Alkene ◽  
Major Producer ◽  
The University ◽  
Linear Product

Nobuaki Kambe of Osaka University found (Tetrahedron Lett. 2009, 50, 5644) that with a Ni catalyst, Grignard reagents coupled preferentially with primary alkyl iodides, even in the presence of the usually reactive ketone. Maurice Santelli of the Université d’Aix-Marseille devised (Tetrahedron Lett. 2009, 50, 5238) a protocol for the conversion of a ketal 4 to the doubly homologated product 6. Brian T. Gregg of AMRI established (Tetrahedron Lett. 2009, 50, 3978; Tetrahedron Lett. 2009, 50, 7070) a procedure for the homologation of a nitrile 7 to the amine 9. Replacement of the NaBH4 with a second Grignard reagent led to the α-quaternary amine (not shown). Toshiaki Murai of Gifu University independently developed (J. Org. Chem. 2009, 74, 5703) a protocol for coupling two Grignard reagents with the linchpin reagent 11 to give the amine 12. Laurel L. Schafer of the University of British Columbia demonstrated (Angew. Chem. Int. Ed. 2009, 48, 8361) Ta-catalyzed intramolecular addition of a methyl amine 14 to the terminal alkene 13 to give 15. Jason S. Kingsbury of Boston College extended (Organic Lett. 2009, 11, 3202) the Roskamp protocol to unstable diazo alkanes such as 17, to give 18. Katsukiyo Miura of Saitama University found (Organic Lett. 2009, 11, 5066) that Pt catalyzed the branched addition of a terminal alkenyl silane 19 to an aldehyde 16 to give the branched adduct 20. Silanes such as 19 are readily prepared directly from the corresponding terminal alkene. Kálmán J. Szabó of Stockholm University observed (J. Org. Chem. 2009, 74, 5695) that the allyl boronate derived from the allylic alcohol 21 could add to the aldehyde 23 to give, depending on the solvent, either the branched product 24 or the linear product 25. The Wittig reaction is a major producer of by-product waste in chemical synthesis. Yong Tang of the Shanghai Institute of Organic Chemistry found (J. Org. Chem. 2007, 72, 6628) that Ph3As could serve catalytically in the condensation of 26 with an aldehyde. Christopher J. O’Brien of the University of Texas at Arlington and Gregory A. Chass of the University of Wales described (Angew. Chem. Int. Ed. 2009, 48, 6836) a related procedure using a cyclic phosphine.

The life and death of laboratory teaching of medical physiology: a personal narrative. Part I.

1993 ◽  
Vol 264 (6) ◽  
pp. S16 ◽  
Author(s):  
H W Davenport
Keyword(s):  
Personal Narrative ◽  
Human Subjects ◽  
University Of Pennsylvania ◽  
Laboratory Course ◽  
Life And Death ◽  
University College ◽  
History Of ◽  
University College London ◽  
Laboratory Teaching ◽  
The University

Part I of this essay sketches the history of laboratory teaching of medical physiology in England from the perspective of the author as a student at Oxford from 1935 to 1938. The systematic laboratory teaching that began in the 1870s at University College London under William Sharpey was carried to Oxford, as well as to other English and Scottish universities, by Sharpey's junior colleagues. C. S. Sherrington added mammalian experiments, and C. G. Douglas and J. G. Priestley added experiments on human subjects. The author describes his experience as a student in the Oxford courses and tells how he learned physiology by teaching it from 1941 to 1943 in the laboratory course established at the University of Pennsylvania by Oxford-trained physiologist Cuthbert Bazett.

Benzene Derivatives: The Tanino-Miyashita Synthesis of Zoanthenol

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Benzoic Acid ◽  
University Of Pennsylvania ◽  
University Of Southern California ◽  
Aryl Chlorides ◽  
National University ◽  
Rh Catalyst ◽  
Nitro Aromatics ◽  
La Jolla ◽  
University Of Oslo ◽  
The University

Yuqing Hou of Southern Illinois University found (J. Org. Chem. 2009, 74, 6362) that the peroxy ether 2 served effectively to directly transfer a methoxy group to the lithiated 1 to give 3. Wanzhi Chen of Zhejiang University, Xixi Campus, showed (J. Org. Chem. 2009, 74, 7203) that pyrimidines such as 4, readily prepared from the corresponding phenol, underwent smooth Pd-catalyzed ortho acetoxylation. Trond Vidar Hansen of the University of Oslo observed (Tetrahedron Lett. 2009, 50, 6339) that simple electrophilic formylation of phenols such as 6 also proceeded with high ortho selectivity. Kyung Woon Jung of the University of Southern California optimized (J. Org. Chem. 2009, 74, 6231) the Rh catalyst for ortho C-H insertion, converting 8 into 9. Jin-Quan Yu of Scripps/La Jolla devised (Science 2010, 327, 315) a protocol for carboxy-directed catalytic ortho palladation that allowed subsequent Heck coupling, transforming 10 into 11. Norikazu Miyoshi of the University of Tokushima established (Chem. Lett. 2009, 38, 996) that in situ generated strontium alkyls added 1,6 to benzoic acid 13, to give, after mild oxidative workup, the 4-alkyl benzoic acid 15. Amin Zarei of Islamic Azad University showed (Tetrahedron Lett. 2009, 50, 4443) that their previously developed protocol for preparing stable diazonium silica sulfates could be extended to the preparation of an aryl azide such as 17. Stephen L. Buchwald of MIT developed (J. Am. Chem. Soc. 2009, 131, 12898) a Pd-mediated protocol for the conversion of aryl chlorides to the corresponding nitro aromatics. Virgil Percec of the University of Pennsylvania has also reported (Organic Lett. 2009, 11, 4974) the conversion of an aryl chloride to the borane, and Guy C. Lloyd-Jones has described (Angew. Chem. Int. Ed. 2009, 48, 7612) the conversion of phenols to the corresponding thiols. Kwang Ho Song of Korea University and Sunwoo Lee of Chonnam National University demonstrated (J. Org. Chem. 2009, 74, 6358) that the Ni-mediated homologation of aryl halides worked with a variety of primary and secondary formamides. Kwangyong Park of Chung-Ang University observed (J. Org. Chem. 2009, 74, 9566) that Ni catalysts also mediated the coupling of Grignard reagents with the tosylate 22 not in the usual way but with the C-S bond to give 23.

New Methods for Carbon-Carbon Bond Construction

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Allylic Alcohol ◽  
Ni Catalyst ◽  
University Of Michigan ◽  
Carbon Carbon Bond ◽  
University Of Technology ◽  
Duke University ◽  
Michael Acceptors ◽  
Leaving Groups ◽  
The University

Mohammad Navid Soltani Rad of Shiraz University of Technology has shown (Tetrahedron Lett. 2007, 48, 6779) that with tosylimidazole (TsIm) activation in the presence of NaCN, primary, secondary and tertiary alcohols are converted into the corresponding nitriles. Gregory C. Fu of MIT has devised (J. Am. Chem. Soc. 2007, 129, 9602) a Ni catalyst that mediated the coupling of sp3-hybridized halides such as 3 with sp3-hybridized organoboranes such as 4, to give 5. Usually, carbanions with good leaving groups in the beta position do not couple efficiently, but just eliminate. Scott D. Rychnovsky of the University of California, Irvine has found (Organic Lett . 2007, 9, 4757) that initial protection of 6 as the alkoxide allowed smooth reduction of the sulfide and addition of the derived alkyl lithium to the amide 7 to give 8. Doubly-activated Michael acceptors such as 11 are often too unstable to isolate. J. S. Yadav of the Indian Institute of Chemical Technology, Hyderabad has shown (Tetrahedron Lett. 2007, 48, 7546) that Baylis-Hillman adducts such as 9 can be oxidized in situ, with concomitant Sakurai addition to give 12. Rather than use the usual Li or Na or K enolate, Don M. Coltart of Duke University has found (Organic Lett. 2007, 9, 4139) that ketones such as 13 will condense with amides such as 14 to give the diketone 15 on exposure to MgBr2. OEt2 and i -Pr2 NEt. Simultaneously, Gérard Cahiez of the Université de Cergy (Organic Lett. 2007, 9, 3253) and Janine Cossy of ESPCI Paris (Angew. Chem. Int. Ed. 2007, 46, 6521) reported that Fe salts will catalyze the coupling of sp2 -hybridized Grignard reagents such as 17 with alkyl halides. John Montgomery of the University of Michigan has described (J. Am. Chem. Soc. 2007, 129, 9568) the Ni-mediated regio- and enantioselective addition of an alkynes 20 to an aldehyde 19 to give the allylic alcohol 21. In a third example of sp2 - sp3 coupling, Troels Skrydstrup of the University of Aarhus has established (J. Org. Chem. 2007, 72, 6464) that Negishi coupling with alkenyl phosponates such as 23 proceeded efficiently.

Organocatalyzed Carbocyclic Construction: (+)-Roseophilin (Flynn) and (+)-Galbulin (Hong)

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Conjugate Addition ◽  
State University ◽  
Max Planck ◽  
University Of Wisconsin ◽  
Georgia State University ◽  
Enantioselective Addition ◽  
The University ◽  
Pais Vasco

Armido Studer of Wilhems-University Münster effected (Chem. Commun. 2012, 48, 5190) the enantioselective conjugate addition of 2 to 1, leading to the cyclopropane 3. Karl Anker Jørgensen of Aarhus University devised (J. Am. Chem. Soc. 2012, 134, 2543) a route to cyclobutanes based on the enantioselective addition of 5 to the nitroalkene 4. Jose L. Vicario of the Universidad del País Vasco reported (Angew. Chem. Int. Ed. 2012, 51, 4104) a similar procedure. Benjamin List of the Max-Planck-Institute Mülheim epoxidized (Adv. Synth. Catal. 2012, 354, 1701) cyclopentenones such as 7 with high ee. Lutz H. Gade of the Universität Heidelberg observed (J. Am. Chem. Soc. 2012, 134, 2946) high ee in the benzylation of 9. Cheng Ma of Zhejiang University formylated (J. Org. Chem. 2012, 77, 2959) cyclopentanone, then condensed the resulting aldehyde 12 with 13 to give 14. Hao Xu of Georgia State University cyclized (Org. Lett. 2012, 14, 858) 15 to the cyclopentenone 16. (+)-Rosephilin 19 inhibits several phosphatases. Bernard L. Flynn of Monash University prepared (Org. Lett. 2012, 14, 1740) the carbocyclic core of 19 by cyclizing 17 to the cyclopentenone 18. Masanori Yoshida of Hokkaido University designed (J. Org. Chem. 2011, 76, 8513) a very simple organocatalyst for the enantioselective conjugate addition of 21 to 20. Samuel H. Gellman of the University of Wisconsin showed (Org. Lett. 2012, 14, 2582) that nitromethane could be added to 23 with high ee. Hiroaki Sasai of Osaka University effected (Angew. Chem. Int. Ed. 2012, 51, 5423) the enantioselective cyclization of the prochiral 25. Ying-Chun Chen of Sichuan University found (Angew. Chem. Int. Ed. 2012, 51, 4401) that the diene 27 could be converted to 29 by way of the intermediate trienamine. Bor-Cherng Hong of the National Chung Cheng University observed (Chem. Commun. 2012, 48, 2385) that under organocatalysis, only one enantiomer of 31 would add to 30, delivering 32 in high ee. Aromatization of 32 led to (+)-galbulin 33.

Arrays of Stereogenic Centers: The Carbery Synthesis of Mycestericin G

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Dipolar Cycloaddition ◽  
General Strategy ◽  
Stanford University ◽  
Keto Ester ◽  
Stereogenic Centers ◽  
Crystalline Adduct ◽  
Enantioselective Addition ◽  
The University ◽  
Pais Vasco

Chi-Ming Che of the University of Hong Kong devised (Chem. Commun. 2011, 47, 11204) a manganese catalyst for the enantioselective cis-dihydroxylation of electron-deficient alkenes such as 1. Christine Greck of Université de Versailles-St-Quentin effected (Tetrahedron Lett. 2012, 53, 1085) enantioselective alkoxylation of 3, remarkably without β-elimination. Keiji Maruoka of Kyoto University developed (J. Am. Chem. Soc. 2012, 134, 7516) an organocatalyst for the enantioselective anti addition of 5 to 6 to give 7. Barry M. Trost of Stanford University developed (J. Am. Chem. Soc. 2012, 134, 2075) a Mg catalyst for the enantioselective addition of ethyl diazoacetate to an aldehyde 8, and carried the adduct onto 9. Professor Maruoka designed (Angew. Chem. Int. Ed. 2012, 51, 1187) for the enantioselective addition of a ketone 10 to the alkynyl ketone 11 to give 12. Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry found (Org. Lett. 2012, 14, 3108) that 14 could be added under very soft conditions to 13 to give the anti adduct 15. René Peters of the Universität Stuttgart added (Adv. Synth. Catal. 2012, 354, 1443) the azlactone formed in situ to 17 in a conjugate sense to give 18. Kaïss Aouadi and Jean-Pierre Praly of the Université de Lyon prepared (Tetrahedron Lett. 2012, 53, 2817) the nitrone 19 from the inexpensive (–)-menthone. Dipolar cycloaddition to a range of alkenes proceeded with substantial diastereocontrol, as illustrated for 20, which gave the crystalline adduct 21. Jeffrey S. Johnson of the University of North Carolina reduced (J. Am. Chem. Soc. 2012, 134, 7329) the α-keto ester 22 under equilibrating conditions to give the lactone 23. Claudio Palomo of the Universidad del País Vasco alkylated (J. Org. Chem. 2012, 77, 747) the aldehyde 24 with 25 to give the diester 26. Damien Bonne and Jean Rodriguez of Aix-Marseille Université added (Adv. Synth. Catal. 2012, 354, 563) the α-keto ester 27 to 28 in a conjugate sense to give 29. Glenn C. Micalizio of Scripps/Florida developed (Angew. Chem. Int. Ed. 2012, 51, 5152) a general strategy for the stereocontrolled construction of skipped-conjugate dienes such as 30.

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