An Unexpected Dihalogenation/Dehydrogenation Product Derived­ via Iodolactonization of an N-Tosyl-N-[6-(2-cyclopenten-1-yl)-2-methylphenyl]glycine

Abstract

The reaction between N-tosyl-N-[6-(2-cyclopenten-1-yl)phenyl]glycine (syn/anti atropisomeric mixture) and molecular iodine is studied. Along with the expected 8-exo-cyclization product possessing a 3-iodo-2,3,3a,6,7,11b-hexahydrobenzo[e]cyclopenta[g][1,4]oxazocine core, the unexpected 1,11b-dehydrogenated/1-iodinated analogue with a 1,3-diiodo-3,3a,6,7-tetrahydrobenzo[e]cyclopenta[g][1,4]oxazocine structure is observed for the first time in a conventional halolactonization reaction.

Halolactonization of N-Acyl-N-(2-cyclohex-1-en-1-yl-6-methylphenyl)glycines: Towards Production of 4,1-Benzoxazoheterocycles

“…The possibility of a similar participation of the tosyl group was previously suggested by us also to explain the mechanism of the unusual direction of the reaction, where the diiodination product was formed. 19 The cyclization of sulfonyl analogues I, according to generally accepted concepts, passes through the stage of initial formation of the bromonium ion A (Scheme 1). In contrast to the benzoyl or acetyl derivatives 4a,b, in the case of mesylates or aryl sulfonates I, the participation of the sulfonyl group in the intermediate transformations through the formation step of the putative transhalogenation/sulfonyloxylation product B probably promotes the generation of allyl halide C. After that, halide C enters into an intramolecular cyclocondensation reaction, which leads to eight-membered heterocycles II (Scheme 1).…”

“…11 The various approaches to the synthesis of the compounds with such backbones make it possible to construct the heterocycles with the required regiolocalization of the nitrogen, oxygen atoms, and functional groups. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] By the interaction of the N-arylsulfonyl (or N-mesyl) glycines I with molecular bromine, we previously obtained the benzoxazocinones II (Scheme 1). 27 Based on generally accepted mechanistic concepts in this field of organic chemistry, it can be assumed that in these halogenation reactions and the subsequent formation of an aryl-fused eight-membered ring several intermediate stages are possible for the conversion of glycine I.…”