| 摘要 |
<p>1496692 Ceph-2-em derivatives CIBAGEIGYAG 27 Jan 1975 [5 Feb 1974] 3362/75 Heading C2C Compounds I (R is 1-7C alkyl, 2-7C alkenyl, 2-7C alkinyl, or heterocyclyl, bonded to the sulphur via a ring carbon atom, which contains 1-4 ring N atoms and optionally a S or O atom and which may be substituted by 1-4C alkyl; R<SP>a</SP> 1 is H or an amino protective group R<SP>A</SP> 1 ; R<SP>b</SP> 1 is H or acyl or R<SP>a</SP> 1 and R<SP>b</SP> 1 together denote a divalent amino protective group; and R 2 is H or a radical R<SP>A</SP> 2 which together with the -COO- grouping forms a protected carboxyl group) and salts thereof are prepared by reaction of a compound II (Y is OH or esterified OH) with a compound R-SH; with the proviso that when using a starting material II where Y is OH or esterified OH, other than CF 3 COO, the reaction is carried out in the presence of an optionally protonic Lewis acid; followed where necessary by conventional chemical modifications.</p> |
