Organocatalytic Knoevenagel condensation by chiral C<sub>2</sub>-symmetric tertiary diamines
作者:Xiaoyu Gu、Yan Tang、Xiang Zhang、Zinbin Luo、Hongfei Lu
DOI:10.1039/c6nj00613b
日期:——
The asymmetric Knoevenagel condensation of aliphatic aldehydes and active methylene compounds catalyzed by (1S,2S)-1,2-diaminocyclohexane-derived catalysts is presented and investigated.
作者:Anna Lee、Anna Michrowska、Sarah Sulzer-Mosse、Benjamin List
DOI:10.1002/anie.201006319
日期:2011.2.11
116 years after the discovery of the Knoevenagelcondensation, the first catalyticasymmetric variant has been developed. Dynamic kinetic resolution in the reaction of α‐branched aldehydes with malonates in the presence of a newly designed and readily available modified cinchona amine catalyst gives the corresponding alkylidene malonates in high enantioselectivity (see scheme).
Intramolecular thermal cyclization and benzannulation reactions of the Gould–Jacobs and Conrad–Limpach types were performed in a designed continuousflow reactor system at temperatures in the range of 300–360 °C and under high pressure conditions (100–160 bar) with very short residence times (0.45–4.5 min) in tetrahydrofuran as a low-boiling point solvent. Substituted heteroaromatic compounds including
The diastereoselectivity in the conjugateaddition of organocopperreagents to γ-aryl α,β-unsaturated carbonyl derivatives 8–14 was investigated. The syn-diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti-diastereoselectivity was obtained in the addition of 10–14 with RCu and RCu(CN)Li (R=Me and Bu) and the syn-selectivity was produced in the addition