| 摘要 |
<p>The following description sets forth a reductive cyclization induced by a trialkyl phosphite of a derivative of formula (II) to give a cephalosporin of formula (I), where A is a protective group of the amino function, R1A is H, a cation or a protecting group of the carboxyl function, X1A is: a) a halogen; b) H; c) -OH, -OR4, -O-COR4, -OSO2R4, -SH, -SR4, -S-COR4, where R4 is a hydrocarbon residue containing 1 to 18 carbon atoms; d) -NR5R6, where R5 and R6, together with N, form a heterocycle; e) -CH2-OR7, where R7 is a C1-C8 alkyl; f) -CH2-S-Het1, where Het1 is a heterocycle; g) -CH=CHG, where G is H; a C1-C3 alkyl or a heterocycle Het2O; Y is =O or =S, and X1B is defined as X1A, provided that it is different from H and from a halogen.</p> |
