Structure–activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles, and -benzothiazoles as an acylation catalyst
synthesized by a condensation reaction of cyclic thioureas 15 and α-bromoacetophenones 14. Investigations of the acylation reactions of 1-phenylethanol with acid anhydrides in the presence of these cyclic isothiourea catalysts revealed their structure–activity relationships. Remarkable electronic effects resulting from substituent(s) on a benzo or phenyl moiety and the influence of the size of the annulating
A number of 2-phenacylisothiouroniumbromides have been prepared from phenacyl bromide and substituted thioureas. The tautomeric nature of the products has been studied spectroscopically. The products have been dehydrated to the corresponding thiazoles.
Dramatic Acceleration of an Acyl Transfer-Initiated Cascade by Using Electron-Rich Amidine-Based Catalysts
作者:Nicholas A. Ahlemeyer、Emma V. Streff、Pandi Muthupandi、Vladimir B. Birman
DOI:10.1021/acs.orglett.7b03044
日期:2017.12.15
A tandem rearrangement of alpha,beta-unsaturated, thioesters into tricyclic ene-lactones fails with conventional amidine-based catalysts, but becomes possible when their electron-rich analogs are employed. A highly diastereo- and enantioselective version of this process has been developed using H-PIP 1b, a chiral catalyst prepared over a decade ago, but never utilized since its disclosure.
Ried,W. et al., Justus Liebigs Annalen der Chemie, 1975, p. 79 - 88
作者:Ried,W. et al.
DOI:——
日期:——
Arya,V.P.; Shenoy,S.J., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1976, vol. 14, p. 759 - 762