Tris(trimethylsilyl)[2H]silane-triethylborane system producing the highly diastereoselective deuteration (> 99:1) of 2′-bromo-2′-deoxy- and 2′-O-phenoxythiocarbonylribonucleosides at 0°C
Reductive protylation and deuteration reactions using (Me3Si)(3)SiH- and (Me3Si)(3)(SiH)-H-2-Et3B systems were investigated in view of the differences in bond energy and bond length between the Si-H of (Me3Si)(3)SiH and the Sn-H of Bu3SnH. Higher diastereoselectivity was obtained in comparison with the reactions using the Bu3SnH - and (Bu3SnH)-H-2-Et3B systems; the (Me3Si)(3)SiH system gave remarkable diastereoselectivity of 98.7% at 0 degrees C, whereas the other system required temperatures below -70 degrees C. (C) 1997 Elsevier Science Ltd.