ChemInform Abstract: Enantioselective Epoxidation of 2,2-Dimethylchromenes Using Achiral Mn- Salen Complex as a Catalyst in the Presence of Chiral Amine.

Benjamin List of the Max Planck Institute, Mülheim devised (J. Am. Chem. Soc. 2008, 130, 6070) a chiral primary amine salt that catalyzed the enantioselective epoxidation of cyclohexenone 1 . Larger ring and alkyl-substituted enones are also epoxidized with high ee. Three- and four-membered rings are versatile intermediates for further transformation. Tsutomu Katsuki of Kyushu University developed (Angew. Chem. Int. Ed. 2008, 47, 2450) an elegant Al(salalen) catalyst for the enantioselective Simmons-Smith cyclopropanation of allylic alcohols such as 3. Kazuaki Ishihara of Nagoya University found (J. Am. Chem. Soc. 2007, 129, 8930) chiral amine salts that effected enantioselective 2+2 cycloaddition of α-acyloxyacroleins such as 5 to alkenes to give the cyclobutane 7 with high enantio- and diastereocontrol. Gideon Grogan of the University of York overexpressed (Adv. Synth. Cat. 2008, 349, 916) the enzyme 6-oxocamphor hydrolase in E. coli . The 6-OCH so prepared converted prochiral diketones such as 8 to the cyclopentane 9 in high ee. Richard P. Hsung of the University of Wisconsin found (Organic Lett. 2008, 10, 661) that the carbene produced by oxidation of the ynamide 10 cyclized to 11 with high de. Teck-Peng Loh of Nanyang Technological University extended (J. Am. Chem. Soc. 2008, 130, 7194) butane-2,3-diol directed cyclization to the preparation of the cyclopentane 15. Note that sidechain relative configuration is also controlled. We established (J. Org. Chem. 2008, 73, 3467) that the thermal ene reaction of 17 delivered the tetrasubstituted cyclopentane 18 as a single diastereomer. Tony K. M. Shing of the Chinese University of Hong Kong devised (J. Org. Chem. 2007, 72, 6610) a simple protocol for the conversion of carbohydrate-derived lactones such as 19 to the highly-substituted, enantiomerically-pure cyclohexenone 21. Hiromichi Fujioka and Yasuyuki Kita of Osaka University established (Organic Lett. 2007, 9, 5605) a chiral diol-mediated conversion of the cyclohexadiene 22 to the diastereomerically pure cyclohexenone 24. Dirk Trauner, now of the University of Munich, reported (Organic Lett. 2008, 10, 149) an elegant assembly of the neuritogenic polyketide shimalactone A 28.

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Arrays of Stereogenic Centers: The Yadav Synthesis of Nhatrangin A

Organic Synthesis ◽

10.1093/oso/9780190646165.003.0040 ◽

2017 ◽

Author(s):

Douglass F. Taber

Keyword(s):

Claisen Rearrangement ◽

Iron Catalyst ◽

Aldol Condensation ◽

State University ◽

Max Planck ◽

Chiral Amine ◽

Cornell University ◽

University Of Oxford ◽

Enantioselective Epoxidation ◽

The University

Miquel Costas of the Universitat de Girona developed (J. Am. Chem. Soc. 2013, 135, 14871) an iron catalyst for the enantioselective epoxidation of the Z-ester 1 to 2. Although the α-chloro aldehyde derived from 3 epimerized under the reaction conditions, Robert Britton of Simon Fraser University showed (Org. Lett. 2013, 15, 3554) that the subsequent aldol condensation with 4 favored one enantiomer, leading to 5 in high ee. Other selective aldol condensations of 4 (not illustrated) have been reported by Zorona Ferjancic and Radomir N. Saicic of the University of Belgrade (Eur. J. Org. Chem. 2013, 5555) and by Tomoya Machinami of Meisei University (Synlett 2013, 24, 1501). Motomu Kanai of the University of Tokyo condensed (Org. Lett. 2013, 15, 4130) D-arabinose 6 with diallyl amine and the alkyne 7 to give the amine 8 as a mixture of diastereomers. Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry combined (Angew. Chem. Int. Ed. 2013, 52, 7310) 9 and 10 to prepare the α-chiral amine 11. Tomoya Miura and Masahiro Murakami of Kyoto University used (J. Am. Chem. Soc. 2013, 135, 11497) an Ir catalyst to migrate the alkene of 13 to the E allyl boronate, that then added to 12 to give 14. Gong Chen of Pennsylvania State University alkylated (J. Am. Chem. Soc. 2013, 135, 12135) the β-H of 15 with 16 to give selectively the diastereomer 17. Geoffrey W. Coates of Cornell University devised (J. Am. Chem. Soc. 2013, 135, 10930) catalysts for the carbonylation of the epoxide 18 to either regioisomer of the β-lactone 19. Yujiro Hayashi of Tohoku University combined (Chem. Lett. 2013, 42, 1294) the inexpensive succinaldehyde 20 and ethyl glyoxylate 21 to give the versatile aldehyde 22. Nuno Maulide of the Max-Planck-Institut für Kohlenforschung Mülheim effected (J. Am. Chem. Soc. 2013, 135, 14968) Claisen rearrangement of 23 to give, after reduction and hydrolysis, the aldehyde 24. Stephen G. Davies of the University of Oxford reported (Chem. Commun. 2013, 49, 7037) a related Claisen rearrangement (not illustrated). Ying-Chun Chen of Sichuan University devised (Org. Lett. 2013, 15, 4786) the cascade combination of 25 and 26 to give 27.

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