Total Syntheses of (−)-Conduritol B ((−)-1L-Cyclohex-5-ene-1,3/2,4-tetrol) and of (+)-Conduritol F((+)-1D-Cyclohex-5-ene-1,2,4/3-tetrol). Determination of the Absolute Configuration of (+)-Leucanthemito

The ‘naked sugar’ (+)-(1R,2R4R)-2-endo-cyano-7-oxabicyclo[2.2.1]hept-5-sn-2-exo-yl acetate ((+)- 4 ) was converted (7 steps, 45% overall) with high stereoselectivity into (?)-(4R,5S,6R)-4,5,6-tris{[(tert-butyl)dimethylsilyl]oxy}cyclohex-2-en-1-one ((?)- 11 ). Reduction of (?)- 1 with NaBH₄- CeCl₃ · 7 H₂O, followed by deprotection of the silyl ether moieties gave (+)-conduritol F ((+)- 1 ; 47%) whose characteristics were identical to those of natural (+)-leucanthemitol. Reduction of (?)- 11 with DIBAH, followed by deprotection of the silyl ether moiety led to (?)-conduritol B ((?)- 3 ; 51 %).