New useful reagents utilizing 1-benzotriazolyl moiety

Abstract

Benzotriazol-1-yl diethyl phosphate (BDP) was conveniently prepared in high yield by the reaction of diethyl chlorophosphate with 1-hydroxybenzotriazole. Various amides were obtained in high yields by simple mixing of carboxylic acid, amine, BDP, and triethylamine in various solvents in high yields. The reaction was complete within 20 min in N,N``-dimethylformamide at room temperature and the corresponding amides were obtained in high yields. It was found that practically no racemization was observed using N,N``-dimethylformamide as a solvent during the supersensitive Young test. Furthermore, various peptides were prepared in high yields without racemization using BDP as a peptide coupling agent. Various esters and thioesters were also prepared by simple mixing of carboxylic acid, an alcohol or a thiol, BDP, triethylamine. But BDP was not effective for the $\beta$-lactam formation from -amino acid and the success of the reaction might depend critically on the structure of $\beta$-amino acids. Similarly, benzotriazol-1-yl diphenyl phosphate and polymer-supported benzotriazol-1-yl diethyl phosphate were prepared under similar conditions to BDP. Those reagents were used for the preparation of amides, or peptides, or $\beta$-lactams. 1,1``-(thiocarbonyldioxy)dibenzotriazole was prepared in high yield by the reaction of thiophosgene with 1-trimethylsilyloxybenzotriazole in methylene chloride. It is noteworthy that this reagent violently exploded at 114$^\circ$C. The reaction of several amines with 1,1``-(thiocarbonyldioxy)dibenzotriazole and triethylamine occurred almost instantly at room temperature to give corresponding isothiocyanates in quantitative yields. t-Butyldimethylsilylation; It is found that DBU is very effective and selective in the t-butyldimethyl-silylation of alcohols, under the present reaction conditions, it is expected that DBU forms complex with t-butyldimethylsilyl chloride which subsequently reacted with alcohols to give t-butyldimethylsilyl e...