The facile synthesis of benzothiazolylideneacetates and 1,4-benzothiazines through a highly controllable oxidation of benzothiazolylacetates

Phenyliodine(III) Diacetate/I2‐Mediated Domino Approach for Pyrrolo[1,4]Thiazines and 1,4‐Thiazines by a One‐Pot Morin Rearrangement of N,S‐Acetals

“…This proceeded through a highly controllable intermediate I followed by sulfenic acid II and the cationic species III [Scheme , Eq. (3)] Two other impractical examples leading to dihydro‐1,4‐thiazines by sulfurolysis, chlorinolysis and also by using sulfuryl chloride have been achieved in moderate yields. We reasoned that aryl‐λ‐iodanes bearing an acetate‐type group could constitute bifunctional reagents.…”

“…At the outset, N,S ‐ acetal 14 a obtained by condensation of cysteamine and ketoester 18 (86 %), was treated with meta ‐chloroperoxybenzoic acid ( m CPBA) (1.2 equiv) in DCM at room temperature similarly to the protocol leading to benzothiazines 13 as outlined above. Unfortunately, the Morin product 15 a (Table , entry 1) was observed as the minor product accompanied by sulfone 19 a , the dimers 21 a / 22 a and other unidentified by‐products that are difficult to isolate pure.…”

Functionalized 1,4‐Benzothiazine: A Versatile Scaffold with Diverse Biological Properties

“…The synthesis of 2‐susbstituted‐ N ‐alkylated‐1,4‐benzothiazines 12 was reported to occur by treatment of benzothiazolylacetates with m ‐CPBA via oxidative ring expansion process 51. On the other hand, the treatment of benzothiazolylacetates with DDQ via dehydrogenation gave benzothiazolylideneacetates 13 .…”

“…On the other hand, the treatment of benzothiazolylacetates with DDQ via dehydrogenation gave benzothiazolylideneacetates 13 . Hence, the synthesis of benzothiazolylideneacetates and 1,4‐benzothiazine was found to be highly controllable via simple exchange of the corresponding oxidants 51 as shown below.…”

Base induced synthesis of 4H-1,4-benzothiazines and their computational studies

“…4,5,10 The most general ones involve cyclocondensation of 2-aminobenzothiazole with a,b-unsaturated acids or esters, or electron decient alkynes; cyclocondensation of 2-aminobenzothiaoles with a-haloketones; condensation and oxidative cyclization of N-unsubstituted and N,N-dialkyldithioanilines with 1,3-dicarbonyls or esters; ring expansions of benzothiazolines using different oxidants like iodine and sulfuryl chloride to synthesize 1,4-benzothiazine and its derivatives. 4,10 Even ring contractions of benzothiazepinones have been also reported in the literature for the synthesis of the above said moieties. 4 The present nding belongs to the ring expansion category using a greener method i.e.…”