2- Methyl-3-substituted-thieno

V. P. Litvinov, T. V. Shchedrinskaya, P. A. Konstantinov, and Ya. L. Gol dfarb, Condensed heteroaromatic sytems including the thiophene ring. 33. Catalytic liquid-phase oxidation of 3-methyl-substituted thieno[2,3-h]thiophene and thieno[3,2-h]thiophene. Khim. Geterotsikl. Soedin., 492 (1975). 

Challenger and Harrison found both thienothiophene 1 and its isomer 2 in the products of the reaction between acetylene and sulfur. To identify these compounds, Challenger et developed syntheses of unsubstituted and 2-alkyl-substituted thieno[3,2-f>]thiophene (2) from thiophene derivatives. Cyclization of (3-thienylthio)acetic acid in the presence of sulfuric acid gave 2,3-dihydrothieno[3,2-6]thiophen-3-one (22) (R = H) in 14% yield reducing the latter with lithium aluminum hydride resulted in thienothiophene (2) formation in 80% yield [Eq. (9)]. Similarly 2-methyl- and 2-ethyl-2,3-dihydrothieno[3,2-/>]thiophen-3-one were obtained from a-(3-thienylthio)propionic and a-(3-tWenylthio)-butyric acids in 30% and 27% yields, respectively their reduction yielded 2-methyl (32%) and 2-ethylthieno[3,2-6]thiophenes (52%). The parent acids were prepared from 3-mercaptothiophene. ... 

Dichloropyridine-4-carboxaldehyde reacts with thiophenol to produce a diaryl sulfide. The diaryl compound and methyl thioglycolate undergo an aldol-type cyclization reaction in the presence of a weak base to afford 4-substituted thieno[2,3-f]pyridine derivative 121 (Scheme 38) <2002JOC943>. 

The 3-substituted thieno[3,2-6]thiophenes were prepared via the same sequence of reactions using the appropriately substituted acetic acid. For example, methyl 2-acetyl-3-thienylthioacetate (173) underwent base-catalyzed condensation to yield, after decarboxylation, 3-methylthieno[3,2-6]thiophene (174 Scheme 59) (76AHC(19)123). 

Strong heating of 2-substituted 5-propargylsulfanyl-3-aryl-3//-pyrimidin-4-ones, and their 5-allylsulfanyl derivatives, has been shown to lead to 2-substituted 3-aryl-6-methyl-3//-thieno[3,2-d]pyrimidin-4-ones and their 6,7-dihydro derivatives. The proposed mechanism in both cases is a [3,3]-sigmatropic thia-Claisen rearrangement followed by tautomerization and a 5-exodig or 5-exo-trig cyclization.38... 

Cycloaddition and cyclization routes were used to access certain 1,3-diazines. The 4+2 cycloaddition reaction of 4-(N-allyl-N-aryl)amino-l,3-diaza-l,3-butadienes with vinyl-, isopropenyl-, and chloroketene led to pyrimidinone-fused pyrimidinones <97T13841>. Cis-cyclopenta[d]pyrimidines were derived from cis-2-amino-l-cyclopentanecarboxylates by cyclization with KOCN and KSCN <97JHC1211>. 2-Thioxopyrido[3, 2 4,5]thieno[3,2-r/]pyrimidin-4(3//)-ones 19 were prepared by cyclocondensation of 2-carbethoxy-3-amino-4-phenyl-6-substituted-thieno[2,3-/)]pyridines and isothiocyanates <97JHC937>. Thiazolyl-benzimidazoles derived from 2-cyanomethyl-l//-benzimidazole and 2,3-dihydrothiazole-2-(3//)-thiones were cyclized to the corresponding thiazolo[4,5-r/]pyrimidines <97PHA346>. Reductive cyclization of 6-cyanomethyl-5-nitropyrimidines afforded 7-alkyl-5//-pyrrolo[3,2-r/]pyrimidines and 6-amino-7,7-dialkyl-7//-pyrrolo[3,2-rf]pyrimidines <97T391>. 7-Methyl-5-alkyl-2-vinyl-pyrazolo[3,4-r/]pyrimidine-4,6(5//,7//)-diones arose from cyclization and alkylation of... 

Design, synthesis, and bioiogical evaluation of 2,4-diamino-5-methyl-6-substituted-thieno[2,3-cdpyrimidine A novei ciassical antifolate with dual thymidylate synthase and dihydrofolate reductase inhibitory acitivity as potential antitumor agent... 

N-phenylmaleimide. The formation of 2-phenacylidene-3-methyl-5-phenyl-l,3-oxazoline by the treatment of the salt (158) with sodium hydride in DMSO was considered to proceed through the thiocarbonyl ylide (159). However, the thiocarbonyl ylide (160), which in a similar manner to that mentioned above was generated from its corresponding dithiolanium salt, instead underwent a spontaneous ring-closure, yielding the spiro-compound (161). The thiocarbonyl ylide dipolar characteristics of phenyl-substituted thieno[3,4-c]pyrroles, phenyl-substituted thieno[3,4-c]thiophens, and the thieno[3,4-/)benzo[c]thiophen (162) have been substantiated by their reactions with dipolarophiles. The first representative (164) of the hitherto... 

Thieno[3,4-d]oxazole-3a(4H)-carboxylic acid, dihydro-2-methyl-synthesis, 6, 1020 Thieno[2,3-d Joxazoles synthesis, 6, 990 Thieno[3,2-g]pteridine structure, 3, 284 lH-Thieno[3,4-c]pyran-2-ones synthesis, 4, 1032 Thienopyrazines synthesis, 4, 1022-1024 Thieno[2,3-6]pyrazines, 4, 1023 electrophilic substitution, 4, 1024 Thieno[3,4-6]pyrazines, 4, 1024 Thieno[3,4-c]pyrazole, 4,6-dihydro-3-hydroxy-carbamates... 

Thieno[3,4-d][ 1,2,3]triazole, tetramethyl-synthesis, 6, 1015 Thieno[3,4-c][ 1,2,3]triazoles synthesis, 6, 1042 Thieno[3,4-d][ 1,2,3]triazoles reactions, 6, 1036 synthesis, 6, 1044 Thienyl radicals generation, 4, 832 Thiepane, 2-acetoxy-synthesis, 7, 574 Thiepane, 2-chloro-nucleophilic substitution, 7, 573 synthesis, 7, 574 Thiepane, 2-methyl-synthesis, 7, 573 Thiepane, 2-phenyl-synthesis, 7, 573 Thiepane, 3,3,6,6-tetramethyl-cycloaddition reactions, 7, 574 Thiepanes, 7, 547-592 applications, 7, 591... 

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