Penem derivative

Scheme 68 shows the conversion of the phenoxymethylpenicillin-derived disulfide (see Scheme 10) to penem derivative (91) (78JA8214). Of particular interest in this sequence is the reductive acylation step to afford (89) and the Wittig ring closure to give (90). The rate of the latter reaction was found to be greatly infiuenced by the steric and electronic character of both the thiol ester and the carboxyl blocking group. 

Scheme 6.218 Synthesis of penem derivatives by azomethine ylide—thione cycloadditions.

R Nagano, Y Adachi, H Imam lira, K Yamada, T Hashizume, H Morishima. Carba-penem derivatives as potential inhibitors of various beta-lactamases, including class B metallo-beta-lactamases. Antimicrob Agents Chemother 43 2497-2503, 1999. 

Table 6.17. SUMMARY OF BIOLOGICAL ACTIVITY OF ISOMERIC A-METHYL TRIAZOLYLMETHYLENE PENEM DERIVATIVES [100]...

This synthetic route preceeded via the novel and versatile intermediate, the 6(5)-bromopenem ester (100) and permitted not only the preparation of large quantities of BRL 42715, but also the preparation of a series of chiral 6-heterocyclylmethylene penem derivatives [99, 100]. 

PCR m polymerase chain reaction, 226-227 Pechmann s 1,2,3-triazole synthesis, 151-152 Penam, 311 Penem derivative, 32... 

Shibuya, M., Kuretani, M. and Kubota, S. (1982) Synthesis of 6-(l-hydroxyethyl)-l,l-dimethyl-l-carba-penem derivatives via Dieckmann-t)fpe cyclization. Tetrahedron Letters, 38, 2659-2655 Hanessian, S. and Reddy, B. (1999) Total synthesis of tricycbc P-lactams. Tetrahedron, 55, 3427-3443. 

Thiacepham (53) was treated with trimethylphosphine to give the thiazepine (54), as a sole product, while treatment of (53) with triphenylphosphine gave the penem derivative (55) (Scheme 19) <82CC809>. 

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