Reversal of Diastereoselectivity of Nitrile Oxide 1,3-Dipolar Cycloadditions by Mg(II). Acceleration of Cycloaddition by Microwave Irradiation
摘要:
1,3-Dipolar cycloadditions of mesitonitrile oxide to Baylis-Hillman adducts (beta-hydroxy-alpha-methylene esters) proceed regioselectively in good yields. Addition of Grignard reagent reverses the diastereoselectivity of the cycloaddition. Microwave irradiation strongly accelerates the reaction with only a small effect on its diastereoisomeric excess. (C) 2000 Elsevier Science Ltd. All rights reserved.
Asymmetric Morita-Baylis-Hillman Reaction: Catalyst Development and Mechanistic Insights Based on Mass Spectrometric Back-Reaction Screening
作者:Patrick G. Isenegger、Florian Bächle、Andreas Pfaltz
DOI:10.1002/chem.201604616
日期:2016.12.5
Morita–Baylis–Hillman (MBH) reaction was developed. By massspectrometric back‐reactionscreening of quasi‐enantiomeric MBH products, an efficient bifunctional phosphine catalyst was identified that outperforms literature‐known catalysts in the MBH reaction of methyl acrylate with aldehydes. The close match between the selectivities measured for the forward and back reaction and kinetic measurements provided
The organocatalytic asymmetric allylic etherification reaction of Morita–Baylis–Hillmancarbonates and silanols was reported for the first time. With modified cinchonaalkaloid (DHQD)2PYR as the catalyst, a series of aromatic, heterocyclic, or aliphatic Morita–Baylis–Hillmancarbonates (25 examples) worked well with triphenylsilanol, affording the corresponding products in moderate to good yields (up