Acetate → (6R, 7R)-Trimethylsilyl 7-[((Trimethylsilyl)oxy)carbonyl]-amino-3-iodomethylceph-3-em-4-carboxylate

Participants

Reaction Steps

To a stirred solution of (6R, 7R)-trimethylsilyl 7-[((trimethylsilyl)oxy)carbonyl]amino-3-acetoxymethylceph-3-em-4-carboxylate in dichloromethane (prepared according to Method B of Example 2; 5.0 g input 7-ACA) was added 3.0 ml (21.1 mmoles, 1.15 equivalents) of TMSI in a slow stream at ambient temperature under a blanket of dry nitrogen. The progress of the reaction was monitored by 1H NMR (acetate region). After a total of 65 minutes, the 1H NMR spectrum of an aliquot of the dark solution shows >95% conversion to the desired (6R, 7R)-trimethylsilyl 7-[((trimethylsilyl)oxy)carbonyl]amino-3-iodomethylceph-3-em-4-carboxylate: NMR (CD2Cl2) δ0.27 (br s, 9H --NHCOOSi(CH3)3), overlapped with CH3COOSi(CH3)3), 0.37 (s, 9H, --COOSi(CH3)3), 3.57 (d, 1H, J=18.1 Hz, --SCH2), 3.80 (d, 1H, J=18.1 Hz, --SCH2), 4.34 (d, 1H, J=9.2 Hz, --CH2I), 4.51 (d, 1H, J=9.2 Hz, --CH2I), 5.00 (d, 1H, J=4.6 Hz, --COCH(N)CH(N)SCH2 --); the remainder of the spectrum was obliterated by protonic dichloromethane.

Provenance & Evidence