The Study On The Stereoselective Wittig And Wittig-Horner Reaction Of L-Lactaldehedes

So far, the investigation about stereochemistry has been a hot spot of chemistry investigator. It's no doubt that stereoselectivity is one aim they go after. On account that Wittig-reaction rightly possess the advantage of stereoselectivity, more and more attention has been attached to Wittig-reaction. Differed from other way of preparation of alkene, it has a special advantage—it's generated alkene has a defitinized position of double bond. In other words, the alkene that Wittig reaction products does not have other isomers because of the shift or rearrangement of double bonds. However, this is not most important, what is the most significant is that it has advanced steroslectivity, which enable the way founded by Wittig has great practical value.This dissertation includes two parts :Part 1 : We summarized the evolvement of the regio- and stereoselective reaction of Wittig and wittig- Horner. Specifically depict of the mechanism of Wittig and wittig- Horner reaction. The regio- and stereoselective problems of Wittig and wittig- Horner reaction has been stressed.Part 2: Due to the emphasize particularly on the impact of Yelide,base, solvent and temperature in the past, the influence of aldehyde's structure to stereoselectivity of Wittig reaction is very little to studied. Therefore, we intend to make a tentative study about that. To make a sterically hinderance inα-position of aldehyde, we give a silicon's protection to hydroxyl group by reaction with TBDMSC1. Through reduction we obtain our initializing material—L-Lactaldehydes . After got the initializing material, we made a series of reaction between -L-Lactaldehydes and some Yelides prepared before experiment. The result of investigation suggested that the regio- and stereoselective influence to production owing to a sterically hinderance of L-Lactaldehydes does exist, although the impact is not great.