Patent ID: 8884031

Claim:
A compound of formula or C: wherein: designates a single or double bond; n is 1, 2, or 3; each of PG 5 and PG 6 is independently a suitable hydroxyl protecting group; W is CH-A or C(O); A is a C 1-6 aliphatic group, wherein A is optionally substituted with one or more Q 1 groups; each Q 1 is independently selected from cyano, halo, azido, oxo, OR, SR, SO 2 R, OSO 2 R, N(R) 2 , NR(CO)R, NR(CO)(CO)R, NR(CO)N(R) 2 , NR(CO)OR, (CO)OR, O(CO)R, (CO)N(R) 2 , O(CO)N(R) 2 , or OPG 1 , wherein PG 1 is a suitable hydroxyl protecting group, and wherein: optionally two Q 1 are on A and are taken together to form a 3-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; each R is independently selected from hydrogen or an optionally substituted group selected from C 1-6 aliphatic, a 5-10 membered saturated, partially unsaturated or aryl carbocyclic ring, or a 4-10 membered saturated, partially unsaturated or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, wherein: when Q 1 is independently selected from N(R) 2 , NR(CO)N(R) 2 , (CO)N(R) 2 , and O(CO)N(R) 2 , two R groups on the same nitrogen atom are optionally taken together with said nitrogen atom to form a 3-8 membered saturated, partially unsaturated, or aryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and wherein X B is O, and R B is TMS; X B is H and OH, and R B is TMS; or X B is H and OAc, and R B is Ac; and R 1 is —CH 2 CO 2 R 2 , wherein R 2 is alkyl.