[GRAPHICS]Under conditions of catalytic Ni(O) and in most cases just over 1 equiv of Me2NH-BH3/K2CO3 or CS2CO3, a Cbz-protected nitrogen, which is part of a heteroaromatic ring, can be chemospecifically cleaved without affecting a Cbz group on an originally basic amine.
Unmodified Nano-Powder Magnetite Catalyzes a Four- Component Aza-Sakurai Reaction
作者:Ricardo Martínez、Diego J. Ramón、Miguel Yus
DOI:10.1002/adsc.200800089
日期:2008.6.9
for an old material: magnetite is an excellent Lewis acid catalyst for the four-component aza-Sakuraireaction. The process could be repeated up to 15-times without losing effectiveness, with the catalyst recycling being as easy as the use of a simple magnet. The catalyst is selective and could discriminate between aldehyde and ketone functionalities, catalyzing first the reaction with the higher electrophilic
A practical procedure for the preparation of carbamates from azides
作者:Xavier Ariza、Fèlix Urpí、Jaume Vilarrasa
DOI:10.1016/s0040-4039(99)01449-5
日期:1999.10
A practicalprocedure for the direct conversion of azides to carbamates has been found. High yields are obtained when primary and secondary aliphatic azides, as well as α-azido esters, are treated in THF with Me3P and several chloroformates (ClCOOBn, ClCOOMe, ClCOOEt, ClCOOCH2CCl3, ClCOOCH2CHCH2).
A variety of storable N-acyl-N-(2,3,4,5,6-pentafluorophenyl)met (4a-e) prepared from N-2,3,4,5,6-pentafluorophenylmethanesulfonamide (3), have been developed after systematic research on the structure-reactivity relationship and were found to serve as N-acylation reagents exhibiting sufficiently good chemoselectivity. (C) 2000 Elsevier Science Ltd. All rights reserved.