Preparation of 6α-monosubstituted and 6,6-disubstituted penicillanates from 6-diazopenicillanates: reactions of 6-diazopenicillanates with alcohols, thiols, phenylseleninyl compounds, and allylic sulphides, and their analogues

Abstract

Reactions of 6-diazopenicillanates (1) and (2) with a range of compounds, in some cases catalysed by BF₃–Et₂O or Cu(acac)₂, have been investigated, and found to be useful for the synthesis of 6α-monosubstituted and 6,6-disubstituted penicillanates. Thus the 6α-alkoxy- and 6α-alkylthio-penicillanates (7)–(15), the 6-phenylselenopenicillanates (26)–(32), and the 6-allyl-6-alkylthio- and 6-ally-6-phenylseleno-penicillanates (39)–(46), were obtained from reactions between 6-diazopenicillanates (1) and (2) and alcohols, thiols, phenylselenol, diphenyl diselenide, phenylseleninyl chloride, allylic sulphides, and allylic selenides. Reactions between 6-diazopenicillanates (1) and (2) and carboxylic acid derivatives and ethers were also briefly examined.

The structure of 2,2,2-trichioroethyl 6α-allyl-6β-phenylthiopenicillanate (39) was confirmed by a single-crystal X-ray study.