Stephan Michel Massoud S, Sterk Damjan, Modec Barbara, Mohar Barbara
PhosPhoenix SARL, 115, rue de l'Abbé Groult, F-75015 Paris, France.
J Org Chem. 2007 Oct 12;72(21):8010-8. doi: 10.1021/jo7014505. Epub 2007 Sep 18.
The ring opening of enantiomerically pure 3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidine-2-borane (1) with a variety of bulky aryllithium reagents was studied. Our results are not in total agreement with those obtained by others. In fact, several 2,6-disubstituted aryl groups were successfully appended to the phosphorus atom, furnishing the corresponding (N-ephedrino)phosphine boranes 2a-g with dr>99:1. However, when the attack on the phosphorus atom is hindered, deprotonation on the benzylic position occurs, leading to the formation of enantiomerically pure trans-(N-methylamino)(phenyl)(1-phenyl-1-propenyloxy)phosphine-P-borane (3). While the attack of 2,2'-dilithio-1,1'-biarenes leads to the corresponding (P-phenyl)phosphole derivatives (4i,j) and to bis(N-ephedrino)phosphine-P-borane (5), the attack of 1,1'-dilithiometallocenes (M=Fe, Ru) leads to a separable diastereomeric mixture of 1,1'-bis[(N-ephedrino)(phenyl)phosphino-P-borane]metallocenes (2k,l/2k',l') with dr approximately 80:20.
研究了对映体纯的3,4-二甲基-2,5-二苯基-1,3,2-恶唑磷硼烷-2-硼烷（1）与多种大体积芳基锂试剂的开环反应。我们的结果与其他人得到的结果并不完全一致。事实上，几个2,6-二取代芳基成功地连接到磷原子上，得到相应的（N-麻黄碱基）膦硼烷2a-g，非对映体比例dr>99:1。然而，当对磷原子的进攻受阻时，苄基位置发生去质子化，导致形成对映体纯的反式-（N-甲基氨基）（苯基）（1-苯基-1-丙烯氧基）膦-P-硼烷（3）。虽然2,2'-二锂代-1,1'-联芳烃的进攻导致相应的（P-苯基）膦环戊二烯衍生物（4i,j）和[双（N-麻黄碱基）]（苯基）膦-P-硼烷（5），但1,1'-二锂代金属茂（M = Fe，Ru）的进攻导致1,1'-双[（N-麻黄碱基）（苯基）膦基-P-硼烷]金属茂（2k,l/2k',l'）的可分离非对映体混合物，非对映体比例dr约为80:20。
