conditions, new selenium-containing heterocycles 10, 2-imino-4-alkylidene-1,3-oxaselenolanes, were obtained via cycloaddition of oxyimidoylselenoates 13 generated in situ by intramolecularaddition of selenolates to carbon−carbontriple bonds.
Selenium-containing heterocycles from isoselenocyanates: synthesis of 2-methylidene-1,3-selenazolidine derivatives
作者:Geoffroy L. Sommen、Anthony Linden、Heinz Heimgartner
DOI:10.1016/j.tet.2006.01.077
日期:2006.4
A convenient and unequivocal synthesis of the title compounds fromisoselenocyanates, malononitrile or 2-cyanoacetate, and 1,2-dibromoethane or α-halogenated carboxylic acid derivatives is reported. The proposed reaction mechanism involves in situ cyclization of different halogenated compounds with an intermediate keten-N,Se-acetal, generated by the base promoted nucleophilic addition of the acidic
Reaction of 2,6-xylyl isoselenocyanate (1) with organolithiumcompounds was examined focussing on the siteselectivities. Phenyllithium attacked selenium exclusively whereas some benzylic organolithiums reacted at the central carbon of 1 to afford the corresponding lithium selenocarboximidates. Phenylethynyllithium and tBuLi gave mixtures of the carbophilic and selenophilic products. The lithium enolate
Selenium-Containing Heterocycles from Isoselenocyanates: Synthesis of 1,3-Selenazinane and 1,3-Selenazinanone Derivatives
作者:Geoffroy L. Sommen、Anthony Linden、Heinz Heimgartner
DOI:10.1002/hlca.200790051
日期:2007.3
The reaction of the intermediate ketene N,Se-hemiacetal 3, prepared from cyanomethylene derivatives 1 by treatment with Et3N and aryl isoselenocyanates 2, with bis-electrophiles 6, 7, 9, and 11 in DMF affords tetrahydro-1H-1,3-selenazine (=1,3-selenazinane) derivatives 8, 10, and 12 in good yield (Scheme 2 and Tables 1–3). Chemical and spectroscopic evidence for the structures of the new compounds
Aluminium‐Catalyzed Selective Reduction of Heteroallenes Through Hydroboration: Amide/Thioamide/Selenoamide Bond Construction and C=X (X=O, S, Se) Bond Activation**
withdrawing groups, experience hydroboration to obtain selectively N-boryl amide, N-borylaminal, and N-boryl methyl amine products. More importantly, a single sustainable molecular aluminum-based catalyst effectively catalyzes CDIs, isocyanates, isothiocyanates, and isoselenocyanates into formamidines, formamides, thioformamides, and selenoformamides, respectively. Further, heteroallene substrates