Preparative access to medicinal chemistry related chiral alcohols using carbonyl reductase technology
摘要:
Libraries of highly enantioenriched secondary alcohols in both enantiomeric forms were synthesised by enzymatic reduction of their parent ketones using selectAZyme (TM) carbonyl reductase (CRED) technology. Commercially available CREDs were able to reduce a range of substrate classes efficiently and with very high enantioselectivity. Matching substrate classes to small subsets of CREDs enabled the fast development of preparative bioreductions and the rapid generation of 100-1500 mg samples of chiral alcohols in typically >95% ee and the majority in >= 99.0% ee. The conditions for small scale synthesis were then scaled up to 0.5 kg to deliver one of the chiral alcohols, (S)-1-(4-bromophenyl)-2-chloroethanol, in 99.8% ee and 91% isolated yield. (C) 2013 Elsevier Ltd. All rights reserved.
The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2 , Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis
This invention provides caspase inhibitors having the formula
1
wherein Ring A is an optionally substituted piperidine, tetrahydroquinoline or tetrahydroisoquinoline ring; R
1
is hydrogen, CHN
2
, R, or —CH
2
Y; R is an optionally substituted group selected from an aliphatic group, an aryl group, an aralkyl group, a heterocyclic group, or an heterocyclylalkyl group; Y is an electronegative leaving group; R
2
is CO
2
H, CH
2
CO
2
H, or esters, amides or isosteres thereof; Ar is an optionally substituted aryl group; and R
3
is hydrogen, an optionally substituted C
1-6
alkyl, F
2
, CN, aryl or R
3
is attached to Ar to form an unsaturated or partially saturated five or six membered fused ring having 0-2 heteroatoms. The compounds are useful for treating caspase-mediated diseases in mammals.
A general catalytic enantioselective trifluoromethylation of aromatic aldehydes using (IPr)CuF and quinidine-derived quaternary ammonium salt as catalysts has been developed. A wide range of aromatic aldehydes are converted to the corresponding products in up to 92% yield and 81% ee at 2 mol% of catalyst loading. (C) 2013 Elsevier B.V. All rights reserved.
Cinchona alkaloid/TMAF combination: Enantioselective trifluoromethylation of aryl aldehydes
The catalytic enantioselective trifluoromethylation reaction of aromatic aldehydes using the Ruppert-Prakash reagent (Me3SiCF3) has been disclosed, with an operationally simple procedure, based on the combination of sterically demanding cinchona alkaloid-derived phase-transfer catalyst 3b with tetramethylammonium fluoride (TMAF). Our methodology provides medicinally important alpha-trifluoromethyl alcohols with high chemical yields and moderate to good enantioselectivities (50-70% ee). (c) 2013 Elsevier B.V. All rights reserved.