Process for the reduction of oxiranyl epothilones to olefinic epothilones

A process to produce a compound of the formulas

• wherein
• W is O or NR8;
• R1, R2, R3, R4, R5, R6, are selected from the group consisting of H, alkyl, substituted alkyl and aryl, and when R1 and R2 are alkyl can be joined to form a cycloalkyl;
• R7 is selected from the group consisting of H, alkyl, substituted alkyl, aryl, cycloalkyl and 4 to 7 membered ring systems having 1, 2, or 3 heteroatoms, wherein the heteroatoms are independently nitrogen, oxygen, or sulfur;
• and
• R8 is selected from the group consisting of H, alkyl, substituted alkyl, OH, O-alkyl, and O-substituted alkyl;
• and
• P1 and P2 are selected from the group consisting of H, alkyl, substituted alkyl, alkanoyl, substituted alkanoyl, aroyl, substituted aroyl, trialkylsiyl, aryl dialkylsilyl, diaryl alkylsilyl, and triarylsilyl;
• which comprises reacting a compound of the formula
• wherein
• W, R1, R2, R3, R4, R5, R6, R7, R8, P1 and P2, are as above;
• with a metal or metal-assisted reagent, wherein said metal or metal-assisted reagent is selected from the group consisting of a) reactive metallocenes;
• b) {N2C(CO2Me)2, cat Rh2,(OAC)4};
• c) {N2C(CO2Me)2, cat{(n-C7H15CO2)2Rh}2};
• d) {Zn—Cu, EtOH};
• e) {Mg(Hg), MgBr};
• f) Cr;
• g) {FeCl3, n-BuLi};
• h) {TiCl3, LiAlH4};
• i) {TiCl4, Zn};
• j) {WCl6, LiAlH4,};
• k) {NbCl5, NaAlH4};
• l) {VCl3, Zn};
• and m) {WCl6, n-BuLi}.