Owing to the high selectivity of the zirconium reagent, all cisenols have been conveniently synthesized by the hydrozirconation of acetylenic alcohols under mild conditions. Gas Chromatographic analysis showed that the products are not contaminated with any detectable amount of trans-enols or the corresponding saturated alcohols. The yield of the cis-enols was 85% when n=1 and increased to 95% when the hydroxyl group is remote from the triple bond. The yield of the enol decreased significantly when n=1 and with alkyl substituents present in the α-carbon of acety-lenic alcohols. It seems that this is due to the steric effect of the bulky O(Zr)group. By protolysis of the hydrozirconation products of the substituted α-alkyl acetylenic alcohols with 2% NH4CL solution all cis-enols can still be obtained. However, by using 3N HCL instead of 2% NH4CL solution, a mixture of cis and trans enols and allyl rearrangement product were obtained. The formation of trans-enol and allyl rearrangement product not only depends upon the condition of protolysis but is also related to the presence of alkyl substituents on the α-carbon atom. Since the formation of carbonium ion from tertiary alcohol or secondary alcohol in acidic condition is more favorable than that from primary alcohol, isomerization and allylic rearrangement will take place in the former case. On the other hand, the hydrozirconation of 1, 1-dimethyl-2-heptyn-1- methyl ether produces sole cis-vinyl ether. These results support our assumption mentioned above.

Key words: MONOHYDRIC ALCOHOL, ORGANO TRANSITION METAL COMPOUNDS, HYDROZIRCONATION, ALKYNE P, METALLOCENES, ENOLS, ZIRCONIUM COMPLEX