Thio-Claisen

Similar to the well-known thio-Claisen rearrangement of allyl aryl sulfides211 and sulfonium salts212, the thio-Claisen rearrangement of allyl aryl sulfoxides has also been reported213. For example, heating of allyl 2-naphthyl sulfoxide (147) at 120 °C for 2h in dimethylformamide resulted in quantitative isomerization to the dihydronaphthothio-... 

Thio-Claisen rearrangement 746-748 Thioketene 5-oxides photolysis of 878 reactions of 277 Thiolane dioxides formula of 382 NMR spectra of 460 reactions of 604 synthesis of 461 Thiolane oxides 747 formula of 382 IR spectra of 461 synthesis of 461, 462, 752 Thiolanes, photolysis of 881 Thiolene dioxides formula of 382 NMR spectra of 460 reactions of 464, 465 synthesis of 461 Thiolene oxides formula of 382 synthesis of 461, 746 Thiols... 

A thio-Claisen rearrangement174 was used for the regioselective synthesis of thiopyrano[2,3-b]pyran-2-ones and thieno[2,3-b]pyran-2-ones (Eq. 12.76). A convenient method for the aromatic amino-Claisen rearrangement of N-(l,l-disubstituted-allyl)anilines led to the 2-allylanilines being produced cleanly and in high yield by using a catalytic amount of p-toluenesulfonic acid in acetonitrile/water (Eq. 12.77).175... 

Ebenfalls mit begleitender Cyclisierung verlauft die Thio-Claisen-Umlagerung bei den Thiophenderivaten 59 und 61 38>. 

The allylation of thiadiazole-2-thione 114 with ally 1 bromide gave as the main product the N-allyl derivative 115 with trace amounts of the corresponding S-derivative 116 (Equation 36) <2003CHE228>. Furthermore, it was shown that refluxing the thiadiazole 116 in DMF (3h) gave thiadiazole-2-thione 115 via a thio-Claisen rearrangement. 

Diastereoselective asymmetric thio-Claisen rearrangement has been carried out by the reaction of thioamides with allyllic bromide (Scheme 37).76... 

Z)-.S -Allylic ketene aminothioacetals underwent thio-Claisen rearrangement at room temperature to give iVjV-dimethyl /1-hydroxy a-allylic thioamides96. /3-I Iydroxy-/V,/V,-dimethylthioamides were deprotonated with LDA to afford a chelated dianion with Z-configuration. Alkylation of this dianion gave the corresponding Z a-hydroxy S-allylic... 

A theoretical study of substituent effects in the thio-Claisen rearrangement (91) -> (92) has been carried out. The study has shown that 2,5-disubstimtion leads to tighter transition states and to a substantial lowering of the enthalpy of... 

In polar aprotic solvents (DMF, DMSO) above 180°C, (2-chloroallyl-thio)- (63) and propargylthiotropones (64) undergo thio-Claisen rearrangements and form thienotropone 65 in good yields [Scheme 17 83H(20)1709]. 

PMR spectroscopy has found wide application in studies of unsubstituted tWenothiophenes, " enophenothiophenes (Table I), > 9 carboxy-, formyl-, bromo-, and adkyl- thienothiophenes, and carboxy- selenopheno-thiophenes. The PMR meAod has also been used to study alkylthieno-[3,2-h]thiophene sulfones and 4,6-dihydrothieno[3,4-h]tMophene (131)9 analyze the mixture of products of the thio-Claisen ... 

The key role of thio-Claisen rearrangements (of 102 - 103) as well as the formation of thiophene byproducts were proved independently148 during attempts to prepare lOld esters. 

Thio-Claisen Rearrangement in the Synthesis of Sulfur-containing Heterocyclic Compounds A. V. Anisimov and E. A. Viktorova, Khim. Geterotsikl. Soedin., 1980, 435-449. 

Thiochromans (1 R = H2) result from disproportionation of 2H- -benzothiopyrans (4) and also from thio-Claisen rearrangements of phenyl allyl sulfides. The first pathway was discovered by Tilak and Vaidya,24 who attempted to prepare one benzothiopyran (15) by cyclizing the /S-ketosulfide (14) in polyphosphoric acid (PPA), but obtained the thiochroman (16) and a benzothiopyrylium salt as in Eq. (5). This reaction involves25,26 an acid-promoted disproportionation... 

Thiochroman (1 R = Ha) is a product of the thio-Claisen rearrangement of allyl phenyl sulfide, as reported in 1963 27 this reaction also produces 2,3-dihydrothiophenes as shown in Eqs. (6) and (7).28,29... 

Similar reactions were carried out on 17,29 18,30 and 19.30 The last gave thiochromans and 2,3-dihydrothiophenes from an apparent cyclization at the ortho methyl substituent, but in fact involving a variety of hydrogen and methyl shifts. The route to the two main products [Eq. (7)] of the thio-Claisen rearrangement has been suggested to be via the thiirane intermediate (20).31... 

The thermolysis of 2-(propargylthio)thiophene (350) and the 3-isomer (351) in the presence of diisopropylamine in a polar solvent such as DMSO led to the formation of the thienothiophenes (56) and (356) in yields of 53% and 65%, respectively. The by-products of these reactions were the thienothiopyrans (354) and (355), which could be conveniently eliminated by treatment with potassium f-butoxide prior to workup. A thio-Claisen rearrangement of (350) and (351) could lead to the presumed allenic thione intermediates (352) and (353), which then rearrange to the observed products (Schemes 121 and 122). In the absence of the amine catalyst, only thienothiopyrans were formed. The ratio of thieno-thiophene to thienothiopyran in the reaction mixture was dependent on the nature of the amine and the solvent used. Diisopropylamine favored the formation of thienothiophenes in... 

The [3,3] sigmatropic rearrangement of allyl vinyl sulfides (thio-Claisen) is particularly easy activation enthalpies can be 10 kcal mob1 lower than for the oxygen analogues [486], and the reaction which was pioneered by Brandsma [487] occurs usually at room temperature and with excellent yields. 

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