Benzo thiochromenes

One general finding of milling studies conducted on hydrate species is that the grinding process serves to lower the dehydration temperatures of ground materials, facilitating the removal of lattice water and formation of an amorphous product. This behavior has been noted for cephalexin [13,14], cefixime [15], cyclophosphamide [18], 2-[(2-methylimidazoyl-l-yl)-methyl]-benzo/ thiochromen-... 

Reaction of the naphthalene-based a,(3-unsaturated thioketone 478 with various acrylate dienophiles leads to the benzo-fused thiochromans 479 from which elimination of the phenylthio group, which may require the addition of base, affords the benzo-fused thiochromenes (Scheme 168) <1992BCJ2056>. These latter products are themselves suitable substrates for hDA reactions which produce dithiabenzo[c]chrysenes 480 <1994BCJ2876>. 

Scheme 45 Coupling-addition-nucleophilic aromatic substitution three-component synthesis of 4//-thiochromen-4-ones 82, 4/f-thiopyrano[2,3-i)]pyridin-4-ones 83, 2-chloro-4/f-thieno[2,3-b] thiopyran-4-ones 84, or 7//-benzo-[b]thieno[3,2-i)]thiopyran-7-ones 85...

The thiochromene 31 is the final product arising from the photoirradiation of tris-(2-benzo-[i]thienyl)methane. The primary photoproduct is a cyclopropane derivative formed by a di-3t-methane rearrangement <03TL751>. 

The base-catalysed reaction of 6-aryl-3-carbomcthoxy-4-methylthio-2//-pyran-2-one 39 with tetrahydrothiopyran-4-onc affords the isothiochroman 40. Similarly, reaction with thiochroman-4-one gives a benzo[c]thiochromene. The carbanion derived from the thiopytanone attacks the pyranone at the electrophilic 6-position with concomitant ring cleavage and loss of CO2. Cyclisation involves nucleophilic attack at the 4-carbonyl function (Scheme 44) <01JOC5333>. 

Heating (208) with hydrobromic acid in acetic acid gave (2-p-nitrophenyl)-benzo[Z)]thiophen. The oxidation of 1-thiochromene with selenium dioxide in boiling ethanol led to 2-(2 -benzo[6]thienyl)-l-thiochromene. " Substituted 2-benzoylbenzo[6]thiophen-3(2JT)-ones have been synthesized by cyclization of... 

Cyclodehydration of the ketone (51) with poly phosphoric acid gives only a small amount of the A -thiochromene (52). The major volatile product is the benzo[b]thiophen (53), probably formed from the thiochromene via a thiiranium intermediate. Irradiation of A -selenochromene at low temperature is reported to give the selenoketone (54). The reaction is reversed thermally."... 

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