ABSTRACT
Conversion of an alpha,alpha-dichloroester to the corresponding alpha-keto acid was unexpectedly complicated by a novel 1,4-homofragmentation. Investigation of the kinetics of this reaction revealed a mechanism involving an alpha-lactone intermediate, which can lead to both the desired alpha-keto acid and the 1,4-homofragmentation, with the product distribution being dependent upon reaction conditions. This information allowed development of a process that affords the alpha-keto acid exclusively and should be generally applicable to the preparation of alpha-keto acids from alpha,alpha-dichloroesters or acids.
Subject(s)
Hydroxy Acids/chemistry , Keto Acids/chemistry , Lactones/chemistry , Kinetics , Molecular StructureABSTRACT
Benzylic and allylic organozinc and Grignard reagents have been added to resin-bound imines to provide alpha-branched secondary amines. Many functional groups, including electrophilic groups, were compatible with this methodology. Three modules--a resin-bound primary amine, an aromatic aldehyde, and the organometallic--were independently varied to produce a combinatorial library of alpha-branched secondary amines designed as beta-3 adrenergic receptor agonists.
Subject(s)
Adrenergic beta-3 Receptor Agonists , Adrenergic beta-Agonists/chemical synthesis , Amines/chemistry , Benzene/chemistry , Imines/chemistry , Zinc/chemistry , Adrenergic beta-Agonists/chemistry , Combinatorial Chemistry Techniques , Molecular Structure , Structure-Activity RelationshipABSTRACT
A survey of several electrophilic ammonia reagents for the N-amination of indole- and pyrrole-containing heterocycles revealed that monochloramine (NH(2)Cl) is an excellent reagent for this transformation. Pyrroles and indoles containing a variety of substitution were aminated on nitrogen with isolated yields ranging from 45% to 97%.
Subject(s)
Chloramines/chemistry , Heterocyclic Compounds/chemistry , Indoles/chemistry , Pyrroles/chemistry , Amination , Molecular StructureABSTRACT
[reaction: see text] An efficient asymmetric synthesis of the vasopeptidase inhibitor BMS-189921 was accomplished. Two short enantioselective syntheses of the common key intermediate (S)-alpha-aminoazepinone 6b were developed. Olefin 3 was converted to 6b via asymmetric hydrogenation. Alternatively, enyne 12 was converted to racemic alpha-aminoazepinone 15b, which was transformed to 6b by a practical dynamic resolution.
