Photochemistry of six- and five-membered-ringα,β-unsaturated lactones in cryogenic matrices

Ultrasonic-assisted Synthetic Improvement of Fluorinated Five- and Six-membered Triazolotriazine and Triazinophthalazine Heterocycles

In this investigation a simple synthetic method for the synthesis of trifluoromethyl-1H-benzo[e][1,2,4]triazolo[1,2-a][1,2,4]triazine-1,3(2H)-diones and (trifluoromethyl)benzo [5,6][1,2,4]triazino[1,2-b]phthalazine-8,13-diones has been developed using urazole or phthalazine and aceteimidoyl chloride derivatives at room temperature under ultrasound irradiations. In the comparison to the conventi...

Synthesis of five-membered osmacycloallenes and conversion into six-membered osmacycloallenes.

Palladium-catalyzed carbocyclization of 1,6-enynes leading to six-membered rings or oxidized five-membered trifluoroacetates.

We describe palladium-catalyzed carbocyclization of 1,6-enynes leading to six-membered rings by water-originated hydride addition. Mechanistic features of this anomalous carbocyclization and isolation of a chiral five-membered C-Pd intermediate as an oxidized form of trifluoroacetate are also reported.

UV-Induced unimolecular photochemistry of diketene isolated in cryogenic inert matrices.

Diketene (C(4)H(4)O(2)) monomers were isolated in cryogenic Ar (15 K) and Xe (30 K) matrices. The infrared (IR) spectra of the freshly deposited matrices show that diketene monomers exclusively adopt the 4-methylene-oxetan-2-one form. In situ photochemical transformations of diketene were induced by tunable UV laser light. Diketene was found to be photostable when exposed to near-UV irradiation...

Bromocyclization of Unsaturated Oximes. Synthesis of Five-Membered Cyclic Nitrones (Pyrroline N-Oxides)* [1]

The cyclization of a ribose-derived pentenose oxime with various halogen electrophiles showed bromine to be the most effective reagent, leading to 80% of L-lyxo/D-ribo-pyrroline N-oxides in an 84:16 diastereomeric ratio. In order to explore the scope of this facile process, several other γ ,δ unsaturated oximes were submitted to this reaction. Depending on the substitution pattern, 23 – 87%, yi...