Highly Stereoselective Chemoenzymatic Synthesis of the 3H-Isobenzofuran Skeleton. Access to Enantiopure 3-Methylphthalides
摘要:
A straightforward synthesis of (S)-3-methylphthalides has been developed, with the key asymmetric step being the bioreduction of 2-acetylbenzonitriles. Enzymatic processes have been found to be highly dependent on the pH value, with acidic conditions being required to avoid undesired side reactions. Baker's yeast was found lobe the best biocatalyst acting in a highly stereoselective fashion. The simple treatment of the reaction crudes with aqueous HCl has provided access to enantiopure (S)-3-methylphthalides in moderate to excellent yields.
Synthesis of synthons: The asymmetric hydrogenation and subsequent in situ lactonization with Ru-diphosphines results in the direct conversion of a series of 2-acylarylcarboxylates including 2-aroylarylcarboxylates into the corresponding optically active 3-substituted phthalides under mild reaction conditions.
Phthalides by Rhodium-Catalyzed Ketone Hydroacylation
作者:Diem H. T. Phan、Byoungmoo Kim、Vy M. Dong
DOI:10.1021/ja907711a
日期:2009.11.4
phthalides by using enantioselective ketone hydroacylation. In the presence of Rh[(Duanphos)]X (X = NO(3), OTf, OMs), various 2-ketobenzaldehydes undergo intramolecularhydroacylation to produce phthalide products in good yields and 92-98% ee's. Our study highlights the key role counterions play in controlling both reactivity and enantioselectivity. A concise asymmetric total synthesis of the celery extract
A facile and convenient synthesis of the chiral phthalide framework catalyzed by cationic iridium was developed. The method utilized cationic iridium/bisphosphine‐catalyzed asymmetric intramolecular carbonyl hydroacylation of 2‐keto benzaldehydes to furnish the corresponding optically active phthalide products in good to excellent enantioselectivities (up to 98% ee ). The mechanistic studies using