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Thiazoline-azetidinone from penicillin

Thiazoline-azetidinones 1 derived from penicillins G and V4) are potential intermediates for penicillin-cephalosporin conversion, where the oxidative functionalization of the methyl group of the 3-methyl-3-butenoate moiety is an essential step. The direct chlorination of 1 with chlorine (25 °C, 3 days) or /-butyl hypochlorite (—60% yields) gives the corresponding chlorinated compounds 2, bearing benzyl, phenyl, p-tolyl, and phenoxymethyl groups as the R3 substituents 5). [Pg.155]

Thiazoline-azetidinone 36 is a versatile intermediate for the synthesis of varieties of beta-lactam antibiotics 24>. The most straightforward route to 36 must be the removal of the feta-lactam A-substituents of thiazoline-azetidinone 35, which is readily obtained from penicillins by Copper s method 4>. This has usually been done by the two-step operation, involving ozonolysis and subsequent methanolysis 25). Direct transformation of 35 to 36 also has been achieved by oxidation with potassium permanganate or osminum tetraoxide, but yields are unsatisfactory (—37%)25). An efficient method for the removal of A-substituents of 35 is the electrochemical acetoxylation procedure which may lead to the compound 36 along with 37 (Scheme 2-12)3). For example, the... [Pg.164]

An alternative electrochemical route to the thiazoline-azetidinone 36 also has been developed. Carboxylic acid 39 prepared from penicillin G can be converted to 36 via 40 by electrochemical decarboxylative acetoxylation followed by hydrolysis (Scheme 2-13)The electrolysis of 39 in an AcOH/DME—AcONa—(C) system at 0 °C... [Pg.165]


See other pages where Thiazoline-azetidinone from penicillin is mentioned: [Pg.1]    [Pg.49]    [Pg.1]    [Pg.49]    [Pg.50]    [Pg.168]    [Pg.194]    [Pg.194]    [Pg.56]   
See also in sourсe #XX -- [ Pg.49 ]




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2-Azetidinone

From Penicillins

Thiazoline

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