Catalytic Enantioselective Construction of β-Quaternary Carbons via a Conjugate Addition of Cyanide to β,β-Disubstituted α,β-Unsaturated Carbonyl Compounds
作者:Yuta Tanaka、Motomu Kanai、Masakatsu Shibasaki
DOI:10.1021/ja1035286
日期:2010.7.7
The first general catalyticenantioselectiveconjugate addition of cyanide to beta,beta-disubstituted alpha,beta-unsaturated ketones and N-acylpyrroles was developed using a strontium catalyst derived from Sr(O(i)Pr)(2) and new chiral ligand 5. The reaction exhibited excellent enantioselectivity and a wide substrate scope using 0.5-10 mol % catalyst. 1,4-Adducts containing beta-quaternary carbons were
Reductive cleavages of homochiral acetalsusing Lewis acid-hydride systems and of alkynyl acetalsusingorganoaluminumreagents are described. Stereochemical outcomes are found to be the opposite compared with our previous results on the aluminum hydride reduction of the acetal.
Tandem Reactions to Construct Heterocycles via Phosphine-Catalyzed Umpolung Addition and Intramolecular Conjugate Addition
作者:Cheng Lu、Xiyan Lu
DOI:10.1021/ol0270733
日期:2002.12.1
[reaction: see text] A highly efficient method for constructing heterocycles was achieved by phosphine-catalyzed tandem umpolung addition and intramolecularconjugateaddition. This strategy offers a simple and promising method for constructing synthetically useful heterocycles under neutral conditions with high atom economy.