Thieno thiadiazine

A suspension of thieno-thiadiazine-4,4-dioxide 187 in a mixture of acetic acidrsulfuric acid water (2 1 1 by volume) which had been heated at 100 °C for4h produced thieno[2,3- -l,2,3-thiadiazole 190 upon neutralization <2000JHC191>. 

Vega and co-workers synthesized a variety of oxazolo[3,2- hetero[l,2,4]thiadiazine-.9,.9-dioxides such as the thieno... 

An unexpected ring contraction reaction has been reported. The attempted hydrolysis of 3-methoxycarbonyl-177-thieno[2,3-< ][l,3,4]thiadiazine 4,4-dioxide 77 under acidic conditions gave the ring-contracted thieno[2,3-<7][l,2,3]thia-diazole 78 instead of the expected carboxylic acid (Equation 24). A similar mechanism to the Hurd-Mori reaction has been proposed for this transformation <2000JHC191>. 

Thieno[3,4-( ]-l,2,4-thiadiazine dioxide 33 and thieno[2,3-i ]-l,2,4-thiadiazine dioxide 34 (prepared as shown in Scheme 8 and Equation (10), Section 10.09.9.1.1) undergo electrophilic substitution on the thiophene ring regio-selectively as shown in Scheme 6 <1997H(45)1767>. 

The parent thieno[3,4- ]-l,2,4-thiadiazine dioxide 35 undergoes regioselective alkylation at N-2 to give, for example, compound 36. This can then be followed by alkylation at N-4 (Scheme 7) <1999BMC2811, 2000EJM751>. 

Photoelectron spectroscopy studies indicate trimethylenesulfur diimide 205 may possibly take up chair and envelope (C4 at the flap) conformations (78ZN284). The benzo[4,5]thieno[3,2-c][lX6,2,6]thiadiazine-4-one 5,5-dioxides (225) exhibit blue fluorescence in long wavelength UV radiation (84CB2779). 

Oxo-3,4-dihydro-l//-thieno[3,4-c][l,2,6]thiadiazine 2,2-dioxide (26) is prepared by a two step procedure from 3-amino-4-methoxycarbonylthiophene involving sulfamoylation of the 3-amino group followed by ring closure (Scheme 7) <89S280>. 

In a related reaction, isopropylsulfamoyl chloride (123) reacts with the enamino esters 32 and 38 to give the sulfonyl analogues of ureas, e.g., 124. Basic ring closure leads then to a benzo[h]thieno[3,4-e]-2,l,3-thiadiazine 2,2-dioxide (125) and a pyrazolo [3,4-e]-2,l, 3-thiadiazine 2,2-dioxide (126), respectively86 (Scheme 30). Similarly, chlorosulfonyi isocyanate (127)87 affords with several enamino esters (after saponification and ring closure... 

A number of reports detailing the preparation of novel fused thiophenes have appeared including tetrahydrobenzothieno[2,3- /]imidazole 226 , dihydrothieno[3,2-g]indazole 227 and dihydrothieno[3,2-AJquinazoline 228 , benzothieno[2,3-Z7]pyridine 229 , thieno[2,3-f ]thiadiazine 230 , thieno[5,6-fc]thiazin-4-one 231 , tetrahydrothieno[3,4-c]pyrid-4-one 232 , and dihydrothieno[4,3,2- /][1.4]benzoxazepine 233 . 

Spiro [2H-l-benzopyran-2,2 -benzothiazolines] spiro [pyrroli din-3,1 -(py rro-lidino-[3,4-c]pyrrolidones)] sydnones thiadiazines thiadi azoles thiaoxaborepanes thiazaphospholanes thiazolo[3,2-a]benzimidazoles thiazolo[3,4-a]benzimidazoles thiazolo[3,2-a][l,3]diazepines thiazolo[2,3-b]quinazolines thieno[2,3-e][l,4]diazepines thieno[2,3-d]pyrimidines... 

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