Our synthetic analysis was guided by the compact nature of ginkgolides for which careful planning of carbon-carbon bond formation is required. As shown in Figure , ginkgolide C (3) could be obtained from intermediate 6 via an aldol reaction to form the C-C bond between C3 and C13 and oxidation reactions at C1, C3, C11 and C12. At the outset, ketone 6 would arise from a 5-exo dig cyclization on the alkyne at C15 preceded by a stereoselective cuprate addition of a tert-butyl group at C8 on enone 7. The latter would be a pivotal intermediate for the synthesis of ginkgolides A (1), B (2) and C (3). We felt that the stereoselective construction of the adjacent quaternary carbon centers (C5 and C9) should be addressed early in the synthesis.To this end, a Sonogoshira coupling reaction using phenylacetylene 10 (C14-C15) followed by alkylation with 9 on spiroalkane 8 (C9-C12) would be considered to install the contiguous quaternary carbon centers. The Pd coupling reaction would not only serve to construct the D-ring lactone, but also to create a steric environment favoring a diastereoselective nucleophilic addition at C9 on spiroalkane 8. The latter could be easily prepared from ketone 11 and allyl alcohol 12, both commercially available, via a Claisen rearrangement securing the first quaternary carbon center at C5 and a ring-closing metathesis (RCM) between C7 and C8 forming the B-ring. The synthesis commenced by the conversion of ketone 11 to the corresponding dimethyl ketal which underwent a Claisen rearrangement with allylic alcohol 12 to generate ketone 3 (Scheme 1A). The B-ring was formed via Grubbs II-catalyzedRCM to afford the ring-closed adduct in 78% yield (over 3 steps), after which, the alkene was conjugated with DBU to afford α,β-unsaturated ester 14 in 99% yield. The ketone was converted to enyne 15 by formation of the corresponding vinyl triflate (96%) followed by a Sonogashira coupling with phenylacetylene 10 (99%). The second quaternary carbon was installed stereoselectively via vinylogous deprotonation of α,β-unsaturated ester 15 with KHMDS/18-crown-6 followed by the addition of iodoalkane 9 to afford α-alkylated ester 16 in 93% (dr >20:1).