Thieno pyrazoles, reaction with

Reaction of the quaternized salts of 4-ethoxycarbonyl-3,5-dimethyl-f-phenylpyttolo(furo or thieno)[2,3-c]pyrazole 34 with the iodomethane quaternary salts of pyridine, quinoline, and isoquinoline in ethanol with catalytic piperidine gave 3-[4(f)]-monomethine cyanine dyes (e.g., 35). Additionally, 3-[2(4)]-trimethine cyanine dyes and 4-[2(4)]-di-3[2(4)]-tri-mixed methine cyanine dyes (e.g., 36 and 37, respectively) were similarly prepared from the intermediates derived by reaction of 34 with triethyl orthoformate in the presence of piperidine (Scheme 8) <2002CCS106f>. 

These methods are limited in scope. Direct thiation has been reported for the transformation of vicinal diketones to [3,4]-annelated thiophenes <1996CHEC-II(7)49>. Thionations and selenations of vicinal halomethyl ketones with thioacetamide or iV,iV-diethylselenopropionamide as sulfur and selenium donors, respectively, have also been reported <1996CHEC-II(7)49>. In a recent example, thieno[3,4-f]pyrazoles 160 were readily prepared from aryl 5-bromomethyl-l//-l-phenylpyrazole-4-yl ketones 159 by reaction with thioacetamide (Equation 35) <1998JHC71>. Additionally, an example of an amination cyclization by reaction of 161 with benzylamine to afford pyrrolo[3,4-i/ thiazole 162 has been described (Equation 36) <1998JHC71>. 

Conversion of ethyl 5-chloropyrazole-4-carboxylate into 4-hydroxy-thieno[2,3-c] pyrazoles, via ethyl 5-(phenylcarbomoylmethylthio)-4-pyrazole carboxylate intermediates, has also been reported (72USP3649641). The reaction of disulfide 313 with nitromethane gives 314 (74TL4069). 

As reported by Mannich (29AP(267)699>, reaction of ethyl cyclopentanone-2-carboxylate with phenylhydrazine and subsequent cyclization of the phenylhydrazone at elevated temperature under strongly basic conditions gives tetrahydro-2-phenylcyclopentapyrazol-3-one (equation 19) (a = b = CH2). The method has been used to prepare thieno[3,4-c]pyrazol-3-ones, thieno[3,2-c]pyrazol-3-ones and pyrrolo[3,4-c]pyrazolones (71JMC454,71JMC1129). 

Reaction of 2,2 -diformyldiphenyldisulfide (27) with nitromethane in the presence of triethylamine gives 2-nitrobenzothiophene (28) (29%).25 Addition of benzoyl peroxide (0.5 mol) increases the yield to 77%. A similar reaction of the pyrazole derivative 29 leads to the thieno[3,2-d]pyrazole 30.25... 

The potent cyclic AMP phosphodiesterase inhibitor (187) was cleaved to (188) and SO2 when treated with sodium methoxide in methanol. The reaction mechanism has been discussed. Irradiation of the pyridinium ylides prepared from thieno[2,3-6]- and thieno[3,2-6]-pyridine by N-amination with O-mesityl-enesulphonylhydroxylamine, followed by treatment with base, resulted in the formation of the corresponding thieno[2,3-c]- and thieno[3,2-c]-17T-l,2-diazepines. From these compounds the corresponding 3//-derivatives, such as (189), were prepared upon photolysis, these gave 3-vinyl-l//-thieno[2,3-c]-pyrazole, while thermolysis yielded 3-(3-thienyl)pyrazole. The 3-acetoxy- and 3-methoxy-derivatives of 3iT-l,2-thienodiazepines were also prepared, and their photolyses gave 3-vinylpyrazole, while thermolysis and treatment with base resulted in loss of nitrogen to give compounds such as (190). ... 

Thieno[3,4-c]pyrazoles.—Cycloaddition of dibenzoylacetylene to N-phenyl-sydnone (78) afforded the pyrazole (79), which, when thionated (P2Ss Pyridine), gave in high yield the stable triphenylthieno[3,4-c]pyrazole (80), the first reported member of this class." Compound (80) enters into cycloaddition reactions, notably with dibenzoylacetylene, with loss of sulphur, giving the diketone (81). Thionation of compound (81) gives, in high yield, the stable blue-black quadricovalent species (82). The mass spectra of... 

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