Mechanism of the Reaction of Olefins with Nitrous Anhydride (O═N–O–N═O) to Form 1,2-Oxazetes

Abstract

The mechanistic pathway for the formation of 1,2-oxazetes by reaction of olefins with nitrous anhydride has been clarified. The initial reaction intermediate, a β-nitroso nitrite ester that is sensitive to light, undergoes O–NO fission to form a β-nitroso alkoxy radical, even with ambient fluorescent lighting but much faster with blue light irradiation. The oxygen of the alkoxy radical subsequently adds to the adjacent nitroso group to generate a cyclic four-membered nitrosyl radical. The 1,2-oxazete is then produced by elimination to generate the CN bond. No 1,2-oxazete formation occurs in the dark.

Preparation of Dinitrogen Trioxide for Organic Synthesis: A Phase Equilibrium Approach

“…85). Reddy et al [163] found that α-cedrene (76) reacts with the N 2 O 3 generated from tetrabutylammonium nitrite ( n Bu 4 N + NO 2 À )/ triflic anhydride (Tf 2 O) to give nitrosonitrite (77) (Eq. 86), which cyclizes to 1,2-oxazetes (78) upon blue light irradiation (Eq.…”

Specific and Strong Acceleration of Nitrosation by Nitrosyl Sulfonates Using the Bis-Coordinating Lewis Acid TiCl4 or SnCl4

“…Nitrosyl triflate ( 1 ), which is readily generated in a CH 2 Cl 2 solution at −20 °C by reaction of triflic anhydride and tetra- n -butylammonium nitrite (1:1 ratio), is a very useful reagent which can convert olefins at −78 °C into cationic 1,2-diazetium ions ( 2 ), which can lead to a variety of reaction products. − For example, cyclooctene ( 3 ) is transformed at −78 °C via the 1,2-oxazetium cation 4 into the products 5 – 8 (Scheme ).…”

Two Unprecedented Reactions of Nitrosyl Triflate: NO+-Induced Cationic Cascade Cyclization and C═C Oxidative Cleavage

“…We recently found that whereas nitrous anhydride (ON-O-NO) reacts with E , E -farnesyl benzoate ( 3 ) at −20 to −30 °C in CH 2 Cl 2 to give the oxazete 4 , nitrosyl triflate reacts at −20 to −30 °C in CH 2 Cl 2 to form the allylic nitroso compound ( 5 ) (Scheme ). , Both reagents were generated in situ in CH 2 Cl 2 at −20 to −30 °C from triflic anhydride and Bu 4 N + ONO – using either a 1:1 ratio for ONOTf or a 1:2 to 1:3 ratio for nitrous anhydride. Remarkably, an entirely different result was obtained when E , E -farnesyl benzoate ( 3 ) was treated with nitrosyl triflate at −78 °C in CH 2 Cl 2 for 3 h. After addition of NaHCO 3 to the reaction mixture and stirring for 30 min with warming to 0 °C and column chromatography on silica gel, the bicyclic oxime 6 was obtained in 86% yield (Scheme ).…”