On the reaction of (vinylimino)phosphoranes and related compounds. 20. Syntheses and properties of methanocyclodeca[b]pyridine ring systems
摘要:
Novel 2-[(triphenyl- and 2-[(tributylphosphoranylidene)amino]-1,6-methanol[10]annulenes (8x,y) and 3-[(triphenyl- and 3-[(tributylphosphoranylidene)amino]-1,6-methano[10]annulenes (9x,y) were generated by the Staudinger reaction of 2- and 3-azido-1,6-methano[10]annulenes (5 and 6). The compound 8x was inert to alpha,beta-unsaturated ketones, while compounds 8y and 9y were found to react with alpha,beta-unsaturated ketones in enamine-alkylation process followed by aza-Wittig reaction and dehydrogenation to give 7,12- and 5,10-methanocyclodeca[b]pyridines 20a-f and 26a,f, respectively. The reactivity of 8 and 9 as well as the site selectivity of 9 was suggested by their C-13 NMR spectra, in which the carbon signals of the nucleophilic center appear at higher field as compared to those of 1,6-methano[10]annulene. Structural properties of 20a-f and 26a,f were examined by H-1 NMR and UV spectra. The H-1 NMR spectra analyzing aromatic characters clarified both remarkable reduction of a ring current and appearance of bond alternation as compared to the parent 1,6-methano[10]annulene (1). The UV spectra exhibiting a prolonged cyclic conjugation are in contrast to their 10-pi electron analogues, 1,6-methano[10]annulene (1) and quinoline derivatives.
Transition-Metal-Free Superbase-Catalyzed C–H Vinylation of Aldimines with Acetylenes to 1-Azadienes
作者:Elena Yu. Schmidt、Ivan A. Bidusenko、Nadezhda I. Protsuk、Yan V. Demyanov、Igor A. Ushakov、Alexander V. Vashchenko、Boris A. Trofimov
DOI:10.1021/acs.joc.9b03192
日期:2020.3.6
Aldimines react with aryl- and hetarylacetylenes in the presence of KOBut/dimethyl sulfoxide (DMSO) or NaOBut/DMSO systems under exceptionally mild conditions (14 °C, 1 h) to afford C-H-vinylated products, 1-azadienes of E configuration relative to the C-C bond, in up to 72% yield. Vinylation involves the unprecedentedly fast multiposition proton transfer in the intermediate adducts of acetylene to
monomethyl ester of the respective dicarboxylicacid was involved in a reaction with imines promoted by acetic anhydride at an elevated temperature. Instead of the initially expected δ-lactam products of the Castagnoli-Cushman-type reaction, medicinally important 3-amino-2-azetidinones were obtained as the result of cyclization, involving a methylene group adjacent to an acid moiety. In contrast, replacing