Chelation-mediated facially selective

Chelation-mediated facially selective cycloaddition reactions.51 The... 

TiCU-mediated addition of silyl enol ether (95) to chiral a-amino aldehyde (94) was reported to proceed with good chelation control, albeit in poor yield (equation 28). Effective chelation control was also reported in the TiCU-mediated reactions of chiral a-alkoxy and p-alkoxy acyl cyanides (96) and (97) with silyl enol ether (95 equations 29 and SO). Reaction of acyl cyanide (97) with the ( )-silyl enol ether (93) gave a single stereoisomer as a result of complete chelation control and syn simple stereoselection (equation 31). Additions of silyl enol ethers and silyl ketene acetals to (-)-menthyl phenyl-glyoxylate and pyruvate were reported to proceed with moderate facial selectivity the best result (84 16) is shown in equation (32). ... 

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