Insertion of Benzynes into the P═N Bond of P-Alkenyl(alkynyl)-λ5-phosphazenes
摘要:
Benzynes, generated from 2-(trimethylsilyl)phenyl triflates, have been found to react with P-Alkenyl-lambda(5)-phosphazenes via a formal pi-insertion into the P=N bond. A subsequent retro [2 + 2] cycloaddition/6 pi electrocyclization/protonation cascade explains the formation of the resulting 1, 4-benzazaphosphorinium trifiates. P-Alkynyi lambda(5)-phosphazenes and phosphane sulfides undergo similar transformations.
5-aminoisoxazolines via tandem catalytic isomerization (of N-allyl systems to N-(1-propenyl) systems)—1,3-dipolar cycloaddition (of a stable nitrileoxide to N-(1-propenyl) systems) is presented. Rhodium and ruthenium complexes, Verkade’s superbase, and 18-crown-6/KOH system were used for the syntheses of the N-(1-propenyl) systems. 4-P-substituted isoxazoline was also synthesized via cycloaddition of
Steric effects on the control of endo/exo-selectivity in the asymmetric cycloaddition reaction of 3,4-dimethyl-1-phenylarsole
作者:Mengtao Ma、Ruifeng Lu、Sumod A. Pullarkat、Weiqiao Deng、Pak-Hing Leung
DOI:10.1039/b924613d
日期:——
The asymmetric cycloaddition reactions of 3,4-dimethyl-1-phenylarsole and (Z/E)-diphenyl-1-propenylphosphine/diphenyl-1-styrylphosphine promoted by a chiral organopalladium(II) complex derived from (S)-[1-(dimethylamino)ethyl]naphthalene proceeded stereoselectively to generate different exo/endo-products. The reactions involving the (Z/E)-methyl substituted phosphines gave the individual optically