Lithium Amino Alkoxide–Evans Enolate Mixed Aggregates: Aldol Addition with Matched and Mismatched Stereocontrol
作者:Janis Jermaks、Evan H. Tallmadge、Ivan Keresztes、David B. Collum
DOI:10.1021/jacs.7b13776
日期:2018.2.28
Building on structural and mechanistic studies of lithiated enolates derived from acylated oxazolidinones (Evans enolates) and chiral lithiated amino alkoxides, we found that amino alkoxides amplify the enantioselectivity of aldol additions. The pairing of enantiomeric series affords matched and mismatched stereoselectivities. The structures of mixed tetramers showing 2:2 and 3:1 (alkoxide-rich) stoichiometries
Studies in macrolide synthesis: A concise asymmetric synthesis of a macrolide intermediate for the erythronolides.
作者:Ian Paterson、David D.P. Laffan、David J. Rawson
DOI:10.1016/s0040-4039(00)80325-1
日期:1988.1
The enantiomerically-pure 14-membered ring macrolide 1 is prepared in 14 steps from the racemic aldehyde 4, Z=SPh. The C2-C4 and C8-C10 stereorelationships in 1 are controlled in a single step by an Evans aldol condensation with (±)-4. Macrolactonisation, 23 → 1, takes place in high yield (91%).
Enantioselective Radical Addition/Trapping Reactions with α,β-Disubstituted Unsaturated Imides. Synthesis of <i>a</i><i>nti</i>-Propionate Aldols
作者:Mukund P. Sibi、Goran Petrovic、Jake Zimmerman
DOI:10.1021/ja043371e
日期:2005.3.1
This manuscript describes a highly diastereo- and enantioselective intermolecular radical addition/hydrogen atom transfer to alpha,beta-disubstituted enoates. Additionally, we show that anti-propionate aldol-like products can be easily prepared from alpha-methyl-beta-acyloxyenoates in good yields and high diastereo- and enantioselectivities.
A highly stereocontrolled route to the monensin spiroketal ring system
作者:David M. Walba、William N. Thurmes、R. Curtis Haltiwanger
DOI:10.1021/jo00240a022
日期:1988.3
Total Synthesis of Oxazole-Based Virginiamycin Antibiotics: 14,15-Anhydropristinamycin IIB