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ABSTRACT: Aza-Morita-Baylis-Hillman (aza-MBH) products derived from arylimines and methyl acrylate or acrylonitrile were N-alkylated with (E)-5-bromopenta-1,3-diene, and the resulting trienes were subjected to intramolecular Diels-Alder (IMDA) cyloadditions to afford the corresponding trans- and cis-fused tetrahydroisoindolines as the major and minor products, respectively. Catalysis with boron trichloride improved the IMDA diastereoselectivities of the nitrile derivatives, while yields were improved in both the nitrile and ester series. Treatment of the nitrile-substituted trienes with DABCO in DMF resulted in unexpected transposition of the N-(pentadienyl)sulfonamide group to the beta-position of the acrylonitrile moiety. Subsequent IMDA cycloadditions produced cis-fused positional isomers of the previous tetrahydroisoindolines. When the products of vinylogous aza-MBH reactions in the nitrile series were N-propargylated, the resulting dienynes underwent a similar transposition and IMDA reaction, producing trans and cis diastereomers of the corresponding dihydroisoindolines as the major and minor products, respectively. In all but one case, only the former products were observed in the presence of methylaluminum dichloride, while the corresponding aromatized isoindolines were obtained when the IMDA reactions were carried out in the presence of DDQ. Thus, a variety of aryl-substituted isoindoline products with different levels of unsaturation and complementary substitution patterns and stereochemistry are readily available through these processes.
The Journal of Organic Chemistry 06/2010; 75(11):3751-60. · 4.45 Impact Factor
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Chemical Reviews 05/2010; 110(8):4498-553. · 40.20 Impact Factor
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ABSTRACT: The aza-Morita-Baylis-Hillman reactions of aldimines 2 with several activated conjugated dienes were found to proceed smoothly in DMF in the presence of 3-hydroxyquinuclidine (HQD). Imines 2 reacted with 1-(p-toluenesulfonyl)-1,3-butadiene (3), methyl 2,4-pentadienoate (6), hexa-3,5-dien-2-one (7), and 1-phenylpenta-2,4-dien-1-one (8) to afford adducts 4, 13, 14, and 15, respectively. While products 4, 13, and 15 were formed as E,Z mixtures, adducts 14 were obtained as essentially pure E-isomers. Cyclization of the E-isomers of the products derived from the dienyl sulfone 3 and the dienoate ester 6 occurred via intramolecular conjugate addition under base-catalyzed conditions to afford functionalized piperidines 5 and 16, respectively. The aza-Morita-Baylis-Hillman reaction and subsequent cyclization of the imine 2a with 3 were also carried out as a one-pot reaction, while the reaction mixture was simultaneously irradiated at 300 nm to effect the photoisomerization of the unreactive Z-adduct of the corresponding 4 to the more reactive E-isomer.
The Journal of Organic Chemistry 05/2007; 72(9):3326-31. · 4.45 Impact Factor
