Intermediates for the preparation of analogs of Halichondrin B

A compound having the formula F-2:

• wherein:
• each is independently a single or double bond, provided that both groups are not simultaneously a double bond;
• LG1 is a suitable leaving group;
• X is —OSO2(Ry);
• Ry is C1-6 aliphatic or a 5-7 membered saturated, partially unsaturated, or fully unsaturated ring, wherein Ry is optionally substituted with up to 3 groups selected from halogen, R, NO2, CN, OR, SR, or N(R)2;
• each R is independently hydrogen, C1-4 haloaliphatic, or C1-4 aliphatic;
• and
• PG3 is a suitable hydroxyl protecting group.