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本文报道了炔醇的锆氢化反应。炔醇和两分子锆氢化试剂在室温反应可使还原产物高选择性地停留于烯醇,所得顺式烯醇的立体选择性高达100％。直链脂族a-炔醇锆氢化产物的产率为79～88％。当炔醇的羟基远离炔键时,由于减少了空间位阻使锆氢化产物的产率有所提高;在炔醇的a碳上有甲基取代基时,由于增加了空间障碍而使顺式烯醇产率下降。此外,后者在强酸介质中,部分异构化为反式烯醇及少量烯丙基型重排产物。本法是从炔醇合成顺式烯醇的一种新方法,它的主要特点是反应条件温和,立体选择性好以及产率较高。
This paper reports the zirconium hydride reaction of alkynols. The reaction of acetylene alcohol with two molecules of zirconium hydride reagent at room temperature allows the reduction product to stay highly selective to the enol, yielding stereoselectivity of up to 100% of the resulting cis-enol. The yield of linear aliphatic a-alkynylaluminium hydride product was 79-88%. When the hydroxyl of acetylenic alcohol moves away from the acetylenic bond, the yield of zirconium hydride product is increased due to the reduction of steric hindrance. When there is methyl substituent on the a carbon of alkynol, due to the increase of steric hindrance, cis Enol yield decreased. In addition, the latter is partially isomerized to trans-enol and a small amount of allyl-type rearrangement products in a strong acid medium. This method is a new method for the synthesis of cis-enol from alkynols. Its main features are mild reaction conditions, good stereoselectivity and high yield.