A New Synthesis of Pyrrolidines by Way of an Enantioselective Mannich/Diastereoselective Hydroamination Reaction Sequence
摘要:
A new two-step synthesis of highly substituted pyrrolidines has been developed. Chiral silane Lewis acid promoted enantioselective Mannich reactions of silyl ketene imines with acylhydrazones may be used to access bishomoallylic benzoic hydrazides that In turn may be cyclized to pyrrolidines by way of the thermal hydroamination reaction reported recently by Beauchemin. Importantly, excellent diastereoselectivity may be realized in the hydroamination reactions.
A New Synthesis of Pyrrolidines by Way of an Enantioselective Mannich/Diastereoselective Hydroamination Reaction Sequence
摘要:
A new two-step synthesis of highly substituted pyrrolidines has been developed. Chiral silane Lewis acid promoted enantioselective Mannich reactions of silyl ketene imines with acylhydrazones may be used to access bishomoallylic benzoic hydrazides that In turn may be cyclized to pyrrolidines by way of the thermal hydroamination reaction reported recently by Beauchemin. Importantly, excellent diastereoselectivity may be realized in the hydroamination reactions.
unprecedented di-π-ethane rearrangement enabled by energy-transfer catalysis under visible light conditions. This innovative open-shell rearrangement boasts broad tolerance toward a range of functional groups, encompassing even complex drug and natural product derivatives. Overall, the reported di-π-ethane rearrangement represents a complementary strategy to the development of radical translocation enabled
alpha-Cyano aldehydes undergo selective transition-metal-catalyzed monoallylation to provide alpha-allylated nitriles. The transformation leads to linear substitution products with palladium catalysts or branched allylated nitriles using an iridium catalyst. Facile TBD-catalyzed retro-Claisen cleavage is leveraged to attain selective monoallylation.
(2-Cyano-2-(phenyl or naphthyl)-2-substituted-ethyl) pyrazines, pyrimidines and pyridazines