ABSTRACT
A synthesis of ß-oxonitriles is reported via the generation of R(1)R(2)CLiCN species followed by the trapping with variously decorated Weinreb amides. The optimization study revealed that lithiation of acetonitriles is best accomplished by deprotonation with MeLi-LiBr at low temperature. The protocol can be conveniently adapted to the synthesis of α-mono or α,α-disubstituted cyanoketones. (15)N- and (17)O-NMR data are reported for selected compounds.
Subject(s)
Amides/chemistry , Cyanoketone/chemistry , Nitriles/chemical synthesis , Methylation , Molecular Structure , Nitriles/chemistryABSTRACT
A highly efficient annulative approach towards the construction of the structurally attractive methylenecyclohexane ring was developed through a convenient 1,4-addition of 4-pentenylmagnesium bromide to 2-cyano-2-cycloalkenones followed by a Pd(II)-mediated oxidative cyclization of the resulting ω-unsaturated α-cyano ketones. Based on this newly developed protocol, polycyclic adducts bearing various ring sizes and substitutions can be prepared in moderate to high yields.
Subject(s)
Acetates/chemistry , Cyanoketone/chemistry , Cyclohexanes/chemistry , Organometallic Compounds/chemistry , Cyclization , Methylation , Molecular Structure , Oxidation-ReductionABSTRACT
A facile iterative synthesis of 2,5-terpyrimidinylenes that are structurally analogous to alpha-helix mimics is presented. Condensation of amidines with readily prepared alpha,beta-unsaturated alpha-cyanoketones gives 5-cyano-substituted pyrimidines. Iterative transformation of the 5-cyano group into an amidine allows synthesis of 2,5-terpyrimidinylenes with variable groups at the 4-, 4'-, and 4''-positions. These compounds are designed to mimic the i, i + 4, and i + 7 sites of an alpha-helix.
Subject(s)
Amidines/chemistry , Biomimetics , Cyanoketone/chemistry , Models, Molecular , Pyrimidines/chemistry , Molecular Structure , Protein Structure, SecondaryABSTRACT
Three man synthetic routes to analogues of tacrine are described: reaction of anthranilonitriles with cyclohexanone and other ketones, reaction of various anilines with alpha-cyanoketones, and reactions involving anilines and cyclic beta-ketoesters. Although tacrine has a wide range of pharmacological effects, it is best known as an inhibitor of cholinesterase enzymes. Many of the analogues that have been made have not been tested against acetylcholinesterase or butyrylcholinesterase activity. Consequently, there is limited information from which a detailed understanding of structure-activity relationships can be derived. However, some halogenated derivatives are not only more potent acetylcholinesterase inhibitors than tacrine, they are also more selective for acetylcholinesterase than for butyrylcholinesterase.
