UV Photoelectron Spectroscopy Studies of the Products of Thermal Extrusion of Sulfur Dioxide from Benzosultams

Abstract

An aza‐ortho‐xylylene system is produced by thermal degradation of N‐alkylbenzosultam, which can be directly studied by coupling the system to a UV/photoelectron spectrometer. These thermodynamically unstable xylylene derivatives rearrange to give aldimine by a [1,5] hydrogen shift.

Aza-ortho-xylylenes in Organic Synthesis

“…[20] No benzoazetine was detected by UV-PES among the products formed during the thermolysis of 2,1-benzisothiazoline 2,2-dioxide. [21] Scheme 4…”

“…[18] A thorough comparison of the results of calculations, semiempirical and ab initio, obtained at various theory levels has been performed by Sander et al [18,19] Results of our ab initio calculations at the MP2 theory level suggest a higher stability for aza-ortho-xylylene (9) than for benzoazetine (5). [21] These calculations also confirm a strong tendency towards [1,5]-hydrogen shifts in N-methyl-aza-ortho-xylylene. [21] According to results of semiempirical AM1 calculations, the 6π electrocyclization of N-acyl-aza-ortho-xylylene to N-acyl-3,1-benzoxazine is more favorable than the 4π electrocyclization to N-acylbenzoazetine (Scheme 36, vide infra).…”

“…[21] These calculations also confirm a strong tendency towards [1,5]-hydrogen shifts in N-methyl-aza-ortho-xylylene. [21] According to results of semiempirical AM1 calculations, the 6π electrocyclization of N-acyl-aza-ortho-xylylene to N-acyl-3,1-benzoxazine is more favorable than the 4π electrocyclization to N-acylbenzoazetine (Scheme 36, vide infra). [22] These calculations also predict higher stabilities than that of benzoazetine for both the (E) and the (Z) isomer of N-acylaza-ortho-xylylene.…”

A Laser Flash Photolysis Study on 2-Azido-N,N-diethylbenzylamine − The Reactivity of Iminoquinone Methides in Solution

“…A number of papers have dealt with their use as reactive dienes in preparative organic chemistry. [2Ϫ7] Other work has been devoted to stabilizing these highly reactive species by complexation to transition metals, [8Ϫ11] and to elucidating their properties and reactivity by using time-resolved techniques, [12Ϫ14] photoelectron spectroscopy, [15,16] or matrix isolation spectroscopy. [17Ϫ19] Quinone methides have received attention for their role in the metabolism of a number of preservatives, [20] for their potential use as anti-cancer agents and as active component of insecticides, [21,22] and for their ability to alkylate DNA efficiently.…”

Benzazetines and their derivatives (review)

“…It was shown [22] that sulfur dioxide is eliminated during the photolysis of 1-methyl-2,1-benzothiazoline 2,2-dioxide (benzosultam 16), and N-methylbenzazetine (18) The work in [23] was concerned with investigation of the products from flash-vacuum thermolysis of various substituted benzosultams by UV photoelectron spectroscopy. It was shown that the formation of some products of this reaction (aldimines) is possible as a result both of migration of a hydrogen atom in the initially formed aza-ortho-xylylenes and of the participation of the corresponding benzazetines.…”