Screening of simple N-aryl and N-heteroaryl pyrrolidine amide organocatalysts for the enantioselective aldol reaction of acetone with isatin
摘要:
We have screened a range of simple N-aryl and N-heteroaryl pyrrolidine amide organocatalysts incorporating N-pyridyl and N-quinolinyl groups in the synthetically useful aldol reaction of isatin with acetone. The 'reverse amide' N-pyridyl pyrrolidinylmethyl amide catalysts proved highly catalytically active but gave disappointing enantioselectivities. However, an N-3-pyridyl prolinamide catalyst gave the aldol adduct in high yields and high enantioselectivity with up to 72% ee of the (S)-isomer. Conditions were optimised for this catalyst and in particular an additive screen identified a link between the pK(a) of the acid additive and the yield and enantioselectivity. An N-arylsulfonamide prolinamide was also identified as a catalyst for this reaction giving the (R)-enantiomer in 68% ee. (C) 2011 Elsevier Ltd. All rights reserved.
The invention related to a novel process, novel process steps and novel intermediates useful in the synthesis of pharmaceutically active compounds, especially renin inhibitors, such as Aliskiren Inter alia the invention relates to a process for the manufacture of a compound of the formula I.
or a salt thereof, wherein R1 as well as Act are as defined in the specification, and processes of manufacturing this compound as well as intermediates in this process.
Screening of simple N-aryl and N-heteroaryl pyrrolidine amide organocatalysts for the enantioselective aldol reaction of acetone with isatin
作者:Michael Kinsella、Patrick G. Duggan、Claire M. Lennon
DOI:10.1016/j.tetasy.2011.07.016
日期:2011.7
We have screened a range of simple N-aryl and N-heteroaryl pyrrolidine amide organocatalysts incorporating N-pyridyl and N-quinolinyl groups in the synthetically useful aldol reaction of isatin with acetone. The 'reverse amide' N-pyridyl pyrrolidinylmethyl amide catalysts proved highly catalytically active but gave disappointing enantioselectivities. However, an N-3-pyridyl prolinamide catalyst gave the aldol adduct in high yields and high enantioselectivity with up to 72% ee of the (S)-isomer. Conditions were optimised for this catalyst and in particular an additive screen identified a link between the pK(a) of the acid additive and the yield and enantioselectivity. An N-arylsulfonamide prolinamide was also identified as a catalyst for this reaction giving the (R)-enantiomer in 68% ee. (C) 2011 Elsevier Ltd. All rights reserved.