Convenient access to two enantiomeric oxirane synthons bearing a quaternary gem-dimethyl carbon center: Synthesis of 3S-(+) and 3R-(−)-2,2-dimethyl-3,4-oxo-1-butanol from R-(−)-pantolactone
Stereoselective Synthesis of 2,6-<i>cis</i>-Tetrahydropyrans through a Tandem Allylic Oxidation/Oxa-Michael Reaction Promoted by the<i>gem</i>-Disubstituent Effect: Synthesis of (+)-Neopeltolide Macrolactone
作者:Hyoungsu Kim、Yongho Park、Jiyong Hong
DOI:10.1002/anie.200903690
日期:2009.9.28
protecting groups is one highlight of a concise and efficient synthesis of (+)‐neopeltolide macrolactone on the basis of the title tandemreaction and dithiane coupling reactions (see scheme). The gem‐disubstituent effect of the dithiane moiety promoted the oxa‐Michael reaction following allylic oxidation to ensure the efficient synthesis of the 2,6‐cis‐tetrahydropyran and high diastereoselectivity.
Synthesis of α,α′-<i>trans</i>-Oxepanes through an Organocatalytic Oxa-conjugate Addition Reaction
作者:Megan L. Lanier、Amanda C. Kasper、Hyoungsu Kim、Jiyong Hong
DOI:10.1021/ol500773w
日期:2014.5.2
Oxepanes are found in a wide range of natural products; however, they are challenging synthetic targets due to enthalpic and entropic barriers. Organocatalytic oxa-conjugate addition reactions promoted by the gem-disubstituent (Thorpe-Ingold) effect stereoselectively provided alpha,alpha'-trans-oxepanes. In addition, the potential of an organocatalytic tandem oxa-conjugate addition/alpha-oxidation was demonstrated in a rapid generation of molecular complexity. These organocatalytic oxa-conjugate addition reactions would provide powerful tools for the synthesis of natural products that contain highly functionalized oxepanes.