Abstract
Chemical transformation of the ester CpMo(CO) 2 (syn-η 3 -1-C 3 H 4 COOMe) to its η 3 -allyl alcohol, acid, acid chloride, and amide has been achieved. Treatment of CpMo(CO) 2 (syn-η 3 -1-C 3 H 4 CHR(OH)) (R = H (2f), CH 3 (2g)) with (CF 3 SO 2 ) 2 O in ether at -78°C stereoselectively generates, the air-stable s-trans-n 4 -diene cations, which have been characterized by appropriate physical methods. The ionization process proceeds via an intramolecular S N 2 mode. The s-trans-η 4 -cis-pentadiene cation reacts with water, alcohol, thiol, and amine to give η 3 -allyl derivatives, which retain the same configuration as that of 2g. The enolate CpMo(CO) 2 (syn-η 3 -1-C 3 H 4 COCH 2 Li) condenses with aldehyde at -78°C to yield the aldol products CpMo-(CO) 2 (syn-η 3 -1-C 3 H 4 COCH 2 CHR(OH)) (R = Ph (6a), CH 3 (6b), (CH 3 ) 2 CH (6c)) with good diastereoselectivity. The major diastereomer has been isolated and characterized by X-ray diffraction. Further reduction of this diastereomer with NaBH 4 produces the corresponding 1,3-diol as a single diastereomer. Utilization of 2g and 6e in synthesis of acyclic 1,3-diol and 1,3,5-triol has been achieved, with excellent stereoselectivity; a mechanism is been proposed.