Paolo Marchini

REACTION BETWEEN 2,2′-DITHIODIANILINE AND ETHYL 2-OXO-1-CYCLOALKANECARBOXYLATES

Abstract A study has been carried out on the acid-catalysed reaction between 2,2′-dithiodianiline (1) and ethyl 2-oxo-1-cycloalkanecarboxylates (2a–d). While the 1,4-benzothiazines 3a, b and benzothiazoles 6a, b are obtained from the keto esters 2a, b, mixtures of the 1,4-benzothiazines 3c, d and 4c, d and benzothiazolines 5c, d are obtained from the keto esters 2c, d. The formation of the benzothiazines 4 falls within the general pattern previously proposed for reactions between 2,2′-dithiodi(aryl- or alkylamines) and ketones. The benzothiazines 3 arise from an acid-catalysed rearrangement of the benzothiazines 4, involving a [1, 3] sulfur migration.

SYNTHESIS AND THERMAL REARRANGEMENT OF 2-ALKOXYCARBONYL-3-ALKYL-4H-BENZO[b][1,4]THIAZINES

Abstract The title compounds (4b-d) together with the benzothiazolines (5b-d) have been obtained by a reaction between 2,2′-dithiodianiline (1) and β-keto esters (2b-d). The reaction between 1 and the β-keto ester 2a gives 1,4-benzothiazine 3a in addition to the benzothiazoline 5a. It has been established that the 1,4-benzothaizines 4b-d undergo an acid-catalysed thermal rearrangement involving a [1,3] shift of the sulfur atom, giving rise to the isomeric 1,4-benzothiazines 3b-d.

REACTION BETWEEN 2,2′-DITHIODIANILINE AND FIVE-MEMBERED RING KETONES

Abstract The acid-catalyzed reaction between 2,2′-dithiodianiline (1) and various five-membered ring ketones yields, in the absence of oxygen, the expected 1,4-benzothiazines. On exposure to air, the latter undergo an autoxidation process, according to a previously described general pathway. From the autoxidation of 12, the hemithioketal 16 has been isolated, and its peculiar properties are discussed.