In the course of our studies on the stereoselective syntheses of biologically active compounds in optically active forms by use of the asymmetric carbons of carbohydreates, the syntheses of (+)-Oxybiotin', (+)-Dethiobiotin2, and (+)-Biotin3 have been already achieved. We would now like to describe the stereoselective syntheses of (+)-and (-)-Avenaciolide from D-glucose and the correct absolute configuration of the natural Avenaciolide. Avenaciolide is a naturally occurring antifungal compound which was first isolated by Brookes, Tidd, and Turner4 from Aspergillus avenaceus. The structure XIIa was assigned by Brookes et a1.4y5. The synthesis of XII in a racemic form was first achieved by Parker and Johnson6 and then by Herrmann, Berger, and Schlessinger7. However, the synthesis of XIIa in an optically active form has not been achieved yet*, we therefore planned the synthesis of XIIa from D-glucose. The starting material 1,2:5,6-di-O-isopropylidene-gD-lyxo-hexofuranos-3-ulose(II) was prepared from D-glucose through D-idose by the method of Paulsen et al.' followed by the method of Tracey et al.". Treatment of II with trim-phosphonoacetate in THF in the presence of n-BuLi gave two unsaturated branched chain carbohydrates, III [lo%, mp 86-87", [&JD 25 -255.3" (c 0.6, CHC13), nmr" 5.15 (lH, m, H2, J1 2=4Hz, J2 vinyl=2HZ), 5.58 (lH, m, H4, J4 vinyl=2H~), 6.18 (lH, t, Hvinyl. J 2 VinylzJvinyl 4 =2H;gdN[80i, mp 69-70", b(]E3 -203.6" (c O.;, CHC13), nmr 4.89 (lH, q. H4, J4'5=4Hz, J4 vif,yl -2Hz), 5.70 (lH, m, H2), 5.96 (lH, d, H1, J1 2=4Hz), 6.0 (lH, t, Hvinyl> J 2, vin;l=Jvinyl,~=2HZ)1' It was expected that the catalytic red&ion of both III and IV would give 3-C-carbomethoxymethyl-3-deoxy-1,2:5,6-di-O-isorpopylidene_B-D-talofuranose (V), since the catalytic reduction of both XV and XVI was known to give 3-C-carbomethoxpethyl-3-deoxy-1,2:5,6-di-0-isopropylidene_O(-D-allofuranose(XVII)'2. As expected, the hydrogenation of III over 10% Pd-C gave V as a sole product [V; quantitative, mp 60-61", co($' -60.1" (c 1.3, CHC13), nmr 4.82 (lH, t, H2, J1 2=J2 3=4Hz), 5.83 (lH, d, H,, J1 2=4Hz)], however, the hydrogenation of IV under the sime cinditions gave two products,'V and 3-C-carbomethoxymethyl-