Aggarwal Varinder K, Bi Jie
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
Beilstein J Org Chem. 2005 Aug 26;1(1):4. doi: 10.1186/1860-5397-1-4.
The degree of reagent and substrate control in the reaction of chiral sulfur ylides with chiral aldehydes has been investigated. Specifically, the reactions of the two enantiomers of the chiral benzyl sulfonium salt 1 with glyceraldehyde acetonide were studied in detail. Of the two new stereogenic centers created, it was found that the C1 stereochemistry was largely controlled by the reagent, whereas control at the C2 center was dependent on the aldehyde used. In one case, the trans isomer was produced via reversible formation of the intermediate betaine, whereas in the alternative case, the C2 center was under Felkin Anh/Cornforth control through non-reversible formation of the betaine. Thus, the aldehyde stereocenter influenced the degree of reversibility in betaine formation, which impacted on the stereocontrol at the C2 position.
对手性硫叶立德与手性醛反应中试剂和底物的控制程度进行了研究。具体而言，对手性苄基锍盐1的两种对映体与丙酮甘油醛的反应进行了详细研究。在所产生的两个新的立体中心中，发现C1立体化学在很大程度上受试剂控制，而C2中心的控制则取决于所使用的醛。在一种情况下，反式异构体是通过中间体甜菜碱的可逆形成产生的，而在另一种情况下，C2中心通过甜菜碱的不可逆形成受费尔金-安（Felkin Anh）/康福思（Cornforth）控制。因此，醛立体中心影响了甜菜碱形成的可逆程度，这对C2位的立体控制产生了影响。
