Highly Enantioselective Hydrogenation of Aromatic-Heteroaromatic Ketones
作者:Cheng-yi Chen、Robert A. Reamer、Jennifer R. Chilenski、Chris J. McWilliams
DOI:10.1021/ol0360795
日期:2003.12.1
Asymmetric hydrogenation of ketone 1 using trans-RuCl(2)[(R)-xylbinap][(R)-daipen] (3) as a catalyst afforded secondary alcohol 2 quantitatively and in 99.4% ee. Further exploration of the effect of the thiazole ring substitution revealed that the catalyst was highly effective for the enantioselectivehydrogenation of 5-benzoyl thiazoles, which afforded corresponding alcohols in 92-99% ee. The same
A Convenient Oxazole C-2 Protecting Group: The Synthesis of 4- and 5-Substituted Oxazoles via Metalation of 2-Triisopropylsilyloxazoles
作者:Ross A. Miller、Randi M. Smith、Benjamin Marcune
DOI:10.1021/jo051490m
日期:2005.10.1
Metalation of oxazoles at the 4 and 5 position was achieved after regioselective C-2 silyl protection. Removal of the protecting group was then accomplished under mild conditions allowing for a straightforward preparation of C-5 monosubstituted and C-4,5 disubstituted oxazoles. The first practical C-2 protecting group of oxazoles has been demonstrated.