Chemistry of cephalosporin antibiotics. XXIX. 3-Halo- and 3-methoxy-3-cephems

Abstract

Recently Schrauzer, et al., discovered that systems which consist of NaBH4, molybdate, and a thiol compound (cysteine, glutathione, or thioglycerol) (designated as Mo-SH systems) can reduce unsaturated

Halide-Terminated N-Acyliminium Ion−Alkyne Cyclizations: A New Construction of Carbacephem Antibiotics

“…As a further development of this theme, a new route to carbacephems is suggested in Scheme . Involvement of an external nucleophile in the pivotal cyclization of glyoxylate-derived N -acyliminium ion 6 would yield a 3-alkylidenecarbacepham 7 . , Oxidative cleavage of the alkylidene unit of 7 would provide a 3-hydroxycarbacephem, an intermediate that has been widely employed to prepare other 3-substituted carbacephems…”

.beta.-Thionolactam analogs of cephalosporins and penicillins

“…Excepting 7 (6)3 and 24 (2)5 substituted cephalosporins (penicillins), these modifications are remote from the [1][2][3][4][5][6][7][8] (1-7) bond, the rupture of which is an essential step in the mechanism of action of /3-lactam antibiotics. To determine the effect of substitution adjacent to this bond, we set out to prepare the /3-thionolactam counterparts of /3-lactam antibiotics.…”

Azetidinone antibiotics. 19. A simple method for the removal of p-nitrobenzyl acid-protective group

“…The crystalline acid was filtered and dried in a vacuum oven overnight. Yield, 3.0 g (83%); NMR (CDCI3 + DMSO-de) 8.02 (s, 3 H, CH3), 5.4 (s, 2 H, PhOCH2), 5.33 (bs, 1 H, C4-H), 4.65 (d, J = 5.0,1 H, Ce-H), 4.36 (q, J = 5 and 9,1 H, C7-H), 3.14-2.52 (m, 5 aromatic H), and 2.1 (d, J = 9.0 Hz, NH). C. 7-Phenoxyacetamido-3-methylenecepham-4-carboxylic Acid 1-Oxide.…”

“…The amorphous residue weighed 600 mg and was made to crystallize by trituration with ether. Yield of pure product; 500 mg (46%); NMR (CDC13 + DMSO-d6) 6.19 (s, 2 H, C2-H2), 5.45 (s, 2 H, «-CH2), 4.97-4.87 (d and s, 3 H, C4-H and C6-H), 4.60 and 4.30 (2s, 2 H, C3-CH2), 4.09 (q, 1 H, C7-H), 3.14-2.52 (m, 5 H, aromatic H), and O. 21 (d. 1 H, amide-NH); IR (Nujol mull) 1668,1735 and 1758 cm-1.…”