Cyclization of Acetylenic Compounds

Boronic acid catalyzed ene carbocyclization of acetylenic dicarbonyl compounds.

The discovery and development of an efficient ene carbocyclization of 1,3-dicarbonyl compounds bearing pendent terminal alkyne substituents under 3-nitrobenzeneboronic acid catalysis is described. The reaction is efficient, easy to perform and general to a wide range of ketoester substrates.

New acetylenic norlignan compounds from rhizomes of Curculigo crassifolia.

Two pairs of diastereoisomeric acetylenic norlignan compounds with PhCH(OR(1))CH(OR(2))CH(2)C triple bond CPh skeleta: (1R, 2R)-1-O-methylnyasicoside (1) and (1S, 2R)-1-O-methylnyasicoside (2), and (1R, 2R)-crassifogenin D (3) and (1S, 2R)- crassifogenin D (4), were isolated from the ethanolic extract of rhizomes of Curculigo crassifolia. Compounds 3 and 4 are new and their structures were eluc...

Pyridine-promoted Cyclization of Functionalized N-Silylated Boron-Nitrogen Compounds

Dichloroboryldisilylamines [SiClm(CH3)3−m]N[Si(CH3)3](BCl2) (m = 1 – 3) as well as chloromethylboryl-bis-(chlorodimethylsilyl)amine [SiCl(CH3)2]2N[BCl(CH3)] form 1 : 1 adducts with pyridine (1 – 4). Those with m = 2 and 3 have been converted into functionalized diazadiboretidine derivatives which are still coordinated by pyridine: [(SiClm(CH3)3−m)NBCl · Py]2 (5: m = 2, 6: m = 3). Single-crystal...

Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization

Hypervalent iodine-mediated regioselective cyclization of acetylenic malonates: facile synthesis of 1-diiodomethylene indane and cyclopentane derivatives.

A facile synthesis of potentially useful 1-diiodomethylene indanes and cyclopentanes from the regioselective cyclization of acetylenic malonates with the combination of iodosobenzene with tetrabutylammonium iodide in 2,2,2-trifluoroethanol is reported.