Lombardo's reagent

Abstract

(A) Stereoselective Synthesis of Orostanal: Orostanal is isolated from, the marine sponge Stelleta hiwasaensis. It shows bioactivity against HL-60 cells at 10 μg/mL. One of the twelve synthetic key steps is the methylenation of a ketone using Lombardo's reagent.4 "Chemical equation presented" (B) Deuterium Labeling: One of the much studied problems is the methylenation of a carbonyl compound to obtain position specific deuterium incorporation. Various methods are limited by their cumbersome nature, loss of label, scrambling, or the presence of other functionalities in the molecule. Specific labeling of deuterium can be achieved by using Lombardo's reagent. 1b "Chemical equation presented" (C) Methylenation of Highly Hindered Ketones: Sterically hindered carbonyl groups can be successfully methylenated using Lombardo's reagent, e.g. in the total synthesis of (±)-kelsoene.5 "Chemical equation presented" (D) Chemoselective Methylenation of Ketones: Carbonyl groups of ketones can be easily methylenated in. the presence of ester carbonyl functionalities without epimerization of adjacent chiral centers. One example is the total synthesis of (-)-(α)-kainic acid.6 "Chemical equation presented" (E) Methylenation of Silyl Ketenes: Modest yields of allenyl silanes were obtained by methylenation of silyl ketenes using Lombardo's approach, whereas the Wittig reagent products were obtained in low yields.7 "Chemical equation presented".