A versatile and efficient route to both enantiomers of 4′-quaternary 2′-deoxy-3′- and -4′-epi-β-C- and -N-nucleosides is described. The asymmetric synthesis involves the SAMP/RAMP-hydrazone α-alkylation methodology and diastereoselective nucleophilic 1,2-additions. Manipulation of the substituents in the anomeric position leads to the thermodynamically more stable β-anomers of excellent diastereo- and enantiomeric purity (>99% de and ee).
介绍了一种获得 4′-季 2′-
脱氧-3′-和-4′-表δ-C-和-N-核苷两种对映体的多功能高效途径。不对称合成涉及
SAMP/
RAMP- 酰
腙δ-烷基化方法和非对映选择性亲核 1,2-加成。通过操纵同分异构体位置上的取代基,可以得到热力学上更稳定的δ-²-异构体,其非对映和对映纯度极高(de 和 ee 均大于 99%)。