1960 年 80 巻 9 号 p. 1199-1201
Four kinds of α-keto ester, (-)-menthyl pyruvate, (+)-bornyl pyruvate, (-)-menthyl phenylglyoxylate, and (+)-bornyl phenylglyoxylate, were reacted with ethynyl-magnesium bromide and the product was hydrolyzed. The optical rotation of atrolactic acid possessing a triple bond so obtained was compared with that of the hydroxy acid obtained by reaction of the foregoing α-keto acids with ethylmagnesium bromide. It was found in the two kinds of pyruvate that ethynyl- and ethyl-magnesium bromides gave atrolactic acid derivative with opposite optical rotation and it was thereby concluded that these two reagents attacked the carbonyl in pyruvate from opposite directions. This fact clearly indicates that ethynyl group is spatially smaller than the ethyl group.