132873-63-3Relevant academic research and scientific papers
Expeditious and Divergent Total Syntheses of Aspidosperma Alkaloids Exploiting Iridium(I)-Catalyzed Generation of Reactive Enamine Intermediates
Tan, Peng Wen,Seayad, Jayasree,Dixon, Darren J.
, p. 13436 - 13440 (2016)
A new approach for the divergent total syntheses of (±)-vincaminorine, (±)-N-methylquebrachamine, (±)-quebrachamine, (±)-minovine and (±)-vincadifformine, each in less than 10 linear steps starting from a single δ-lactam building block, is reported. Key to our route design is the late-stage generation of reactive enamine functionality from stable indole-linked δ-lactams via a highly chemoselective iridium(I)-catalyzed reduction. The efficiently formed secodine intermediates subsequently undergo either a formal Diels–Alder cycloaddition or a competitive Michael addition/reduction to access aspidosperma-type alkaloids in excellent diastereoselectivities. Product selectivity could be controlled by changing the indole N-protecting group in the reductive cyclization precursors. An asymmetric variant of this synthetic strategy for the synthesis of (+)-20-epi-ibophyllidine is also described.
Synthesis and decarboxylation of Δ2-cephem-4,4-dicarboxylic acids
Wolfe,Ro,Kim,Shi
, p. 1238 - 1258 (2007/10/03)
Penicillin V was converted in 14 steps into Δ2-cephems having hydrogen at C-3, hydrogen or methyl at C-2, and two methoxycarbonyl, two benzyloxycarbonyl, or one methoxycarbonyl and one benzyloxycarbonyl substituent at C-4. Deprotection of these Δ2-cephem-4,4-dicarboxylic acid esters by alkaline hydrolysis (in the case of methyl esters) or hydrogenolysis (in the case of benzyl esters) led in all cases to rapid decarboxylation of the Δ2-cephem-4,4-dicarboxylic acid or Δ2-cephem-4,4-dicarboxylic acid monoester. With hydrogen at C-2, hydrolysis of the dimethyl ester with 1 equiv of base produced a Δ2-cephem. With 2 equiv of base, and with all compounds having methyl at C-2, hydrolysis or hydrogenolysis afforded 4α-substituted-Δ2-cephems. In contrast, simpler benzyl or methyl acetamidomalonates could be deprotected without difficulty to afford stable malonic acids. Reasons for the differences in ease of decarboxylation were examined using semiempirical (AM1) and ab initio (3-21G) molecular orbital calculations. The decarboxylation barriers of unionized cephem or acetamido malonic acids were found to be high (35-40 kcal mol-1). Although the monoanion of acetamidomalonic acid retained a high barrier, the epimeric monoanions of a Δ2-cephem malonic acid decarboxylated with barriers of only 2 kcal mol-1.
Heterocyclic amines having central nervous system activity
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, (2008/06/13)
Tricyclic nitrogen containing compounds, having central nervous system activity of the following structural formula: STR1 and pharmaceutically acceptable salts thereof wherein R1, R2, and R3 are independently hydrogen, C1-6 alkyl, alkenyl, or alkynyl, C3-10 cycloalkyl, or R1 and R2 are joined to form a C3-7 cyclic amine which can contain additional heteroatoms; X is hydrogen, C1-6 alkyl halogen, hydroxy, alkoxy, cyano, carboxamide, carboxyl, or carboalkoxyl; A is SO2, N, CH, CH2, CHCH3, C=O, C=S, C-SCH3, C=NH, C-NH2, C-NHCH3, C--NHCOOCH3, or C--NHCN. B is CH2, CH, C=O, N, NH or N--CH3 ; n is 0 or 1; and D is CH, CH2, C=O, O, N, NH or N--CH3. These new compounds are suitable for treating schizophrenia, Parkinson's disease, anxiety, depression or as compounds for lowering blood pressure in animal or human hosts.
