Derivatized virginiamycin M.sub.1

A process for preparing a virginiamycin derivative of the formula ##STR6## and isomeric forms and mixtures thereof, in which S represents a sulfur atom, Y represents one of (CH.sub.2).sub.n (n=1 to 20), (CH.sub.2).sub.m CH[(CH.sub.2).sub.n CH.sub.3 ](CH.sub.2).sub.p (m=0 to 20, n=0 to 20, p=0 to 20), and ##STR7## (m=0 to 10, n=0 to 10, p=1 to 10, q=0 to 10), or unsaturated derivatives thereof wherein adjacent pairs of saturated carbon atoms are replaced by alkene or alkyne units;

• and Z represents one of CO.sub.2 CH.sub.2 CCl.sub.3, CO.sub.2 (CH.sub.2).sub.n CH.sub.3, CO.sub.2 (CH.sub.2).sub.m CH[(CH.sub.2).sub.n CH.sub.3 ](CH.sub.2).sub.p CH.sub.3, CO.sub.2 (CH.sub.2).sub.m (CH.dbd.CH)(CH.sub.2).sub.n H, CO.sub.2 H, CONH.sub.2, CONHR (R=saturated or unsaturated n-alkyl or branched alkyl as shown for the esters above), CONRR' (R and R'=saturated or unsaturated n-alkyl or branched alkyl as shown for the esters above), and CO.sub.2.sup.- M.sup.+ (M.sup.+ =lithium, sodium, potassium, cesium, magnesium, or calcium cation, with or without other coordinating groups, or ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, or tetraalkylammonium bearing n-alkyl or branched alkyl groups as shown for the esters above, or ammonium salt derivatives of amino acids), comprising:
• reacting a .omega.-mercapto ester having the formula SYZ, wherein S, Y and Z are as defined above, with a virginiamycin M.sub.1 sample having the formula:
• ##STR8## in an organic solvent in the presence of a base, said reaction occurring under reaction conditions conducive for attachment of the SYZ side chain to said virginiamycin M.sub.1 via a Michael addition.

A process for preparing a virginiamycin derivative of the formula ##STR9## and isomeric forms and mixtures thereof, in which S represents a sulfur atom, Y represents one of (CH.sub.2).sub.n (n=1 to 20), (CH.sub.2).sub.m CH[(CH.sub.2).sub.n CH.sub.3 ](CH.sub.2).sub.p (m=0 to 20, n=0 to 20, p=0to 20), and ##STR10## (m=0 to 10, n=0 to 10, p=l to 10, q=0 to 10), or unsaturated derivatives thereof wherein adjacent pairs of saturated carbon atoms are replaced by alkene or alkyne units;

• and Z represents one of CO.sub.2 CH.sub.2 CCl.sub.3, CO.sub.2 (CH.sub.2).sub.n CH.sub.3, CO.sub.2 (CH.sub.2).sub.m CH[(CH.sub.2).sub.n CH.sub.3 ](CH.sub.2).sub.p CH.sub.3, CO.sub.2 (CH.sub.2).sub.m (CH.dbd.CH)(CH.sub.2).sub.n H, CO.sub.2 H, CONH.sub.2, CONHR (R=saturated or unsaturated n-alkyl or branched alkyl as shown for the esters above), CONRR' (R and R'=saturated or unsaturated n-alkyl or branched alkyl as shown for the esters above), and CO.sub.2.sup.- M.sup.+ (M.sup.+ =lithium, sodium, potassium, cesium, magnesium, or calcium cation, with or without other coordinating groups, or ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, or tetraalkylammonium bearing n-alkyl or branched alkyl groups as shown for the esters above, or ammonium salt derivatives of amino acids), comprising:
• reacting a virginiamycin M.sub.1 sample having the formula ##STR11## with a silyl ether under conditions conducive for attaching said silyl ether to the C-14 hydroxyl group of said virginiamycin M.sub.1 sample, thereby obtaining a C-14 protected virginiamycin M.sub.1 sample;
• reacting a .omega.-mercapto ester having the formula SYZ, wherein S, Y and Z are as defined above, with said C-14 protected virginiamycin M.sub.1 sample in an organic solvent in the presence of a base under reaction conditions conducive for attachment of the SYZ side chain to said virginiamycin M.sub.1 ;
• and
• removing said silyl ether from said C-14 hydroxyl group.