Unexpected highly diastereoconvergent Grignard additions to D-xylofuranose-derived t-butanesulfinyl aldimines

Unexpected high levels of diastereoconvergence (dr >15:1) were observed in the addition of a series of Grignard reagents in THF to D-xylose-derived t-BS aldimines 2a,b affording (S-S,5R)- and (R-S,5R)-adducts. This anomaly was absent when using ethereal solutions of organometallic reagents, revealing the subtle solvent effects. This study illustrates the scope and limitations of N-t-BS imine chemistry in complex systems. (C) 2011 Elsevier Ltd. All rights reserved.