The synthesis of beta-lactams from allyl- and (allenylmethyl)silanes, such as (167) and (256), was achieved by a combination of the olefin/CSI approach to beta-lactams, developed by Graf, and the Na2SO3 reduction system used by Durst and O'Sullivan. The Asparenomycin precursor (259) was synthesised from the TBDMS- protected allene (256) and CSI, with the regiochemistry of the process controlled by the beta-effect of silicon. Attempts were made to incorporate the oxidatively cleavable -SiMe2OiPr moiety in the synthesis of the Asparenomycin precursor (259), some success being achieved with the synthesis of the allene (270). Cycloaddition of this allene (270) failed to yield the corresponding p-lactam (271). Allyl/vinyldisilanes, such as (315), were transformed into the corresponding beta-lactams, (318), by treatment with CSI, followed by reductive work-up with Na2SO3. Incorporation of the oxidatively cleavable -SiMe2OiPr moiety into beta-lactam (321), followed by oxidation with H2O2 and bis-silylation, yielded the silylated 4-hydroxymethyl-beta-lactam (332) in 75% yield, a useful carbapenem precusor. Peterson olefination of beta-lactam (349), using LDA and the hypernucleophilic agent DMEU, resulted in production of the C-3 alkylidene beta-lactam (357) in 30% isolated yield. With the furylsilyl beta-lactam (342) a similar result was obtained, but separation of product and starting material proved impossible. The phenylsilyl beta-lactam (355) showed no C-3 alkylidene product under the optimised conditions developed during these investigations.
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