Table, 2nd row of last column should read: Te-Te? 604 (tmm), 680 (cis).

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The nocardicin skeleton has been s'iereospecifically synthesised from readily available penicillin derivatives.ATTENTIOX has been paid recently to the synthesis1v2 of nocardicin A (la), a monocyclic ,&lactam antibiotic isolated from Nocardia z.tnifoi/nzis.3 During a study of the preparation of novel p-lactarn antibiotics, we devised a synthetic access to the class of compounds (6), closely related to nocardicin. which has the advantage of introducing the desired final side chain R3 a t an early stage. This procedure by-passes 3-ANA (lb), which has been a necessary intermediate in previous syntheses.ly2Treatment of the thiazoline (2), obtained from penicillin G by an estrzblished r ~u t e , ~? ~ with (*)-methyl ol-bromophenylacetate in the presence of NaH a t 0 OC, gave a 30% yield, after crystallisation of the crude product from Et,O, of the synthon (3, R1 2 11, = H ) ; [Ex], -175" (CHC1,); 8(60 MHz, CDCl,) 3.74 (s, Y e 0 and CH,), 5.57 (s, exocyclic C-H), 576-6.05 (m, 13-lactam H), and 6.9-7.6 (m, Ar-H).

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