2- Phenyl-l ,3-dithiane

Stirring is continued for 2 hours at room temperature, and then methanol is added until a clear solution is obtained (ca. 10 ml. of methanol is required, and some heat is generated). When the solution has cooled, it is washed successively with 200 ml. of aqueous 2N potassium carbonate and 200 ml. of water. The aqueous phases are combined, washed with three 100-ml. portions of chloroform, and discarded. The organic phases are then combined, dried over sodium sulfate, and decolorized with activated carbon. Concentration of the chloroform solution thus obtained provides three crops of pale yellow crystals, which are washed with 30% hexane in chloroform and dried for 2 hours at 80°/0.1 mm. The total yield of 3-(2-phenyl-l,3-dithian-2-yl)indole is 22.3-25.4 g. (72-81%), m.p. 167-169° (Note 7). This material requires no further purification for use in Parts D or E. 

L//-Indole, 3<2-phenyl-l, 3-dithian-2-yl), 10 Indoles, 34 Indoles, 3-acyl-, 8 Indoles, 3 -alkyl, 8 Isocyanate, chlorosulfonyl [Sulfuryl chlonde isocyanate], 41 Isocyanate,2-propyl- [Propane, 2-iso-cyanato-], 96... 

Some cyclic thioacetals have an A-SE2 hydrolysis mechanism,206 as do some 2-aryl-2-methyl-l,3-dithianes, except for the 4-NO2 derivative, which looks more A2-like.207 In 10 vol% dioxane/aqueous HC104 mixtures, reactive 2-aryl-2-phenyl-l,3-dithianes are believed to have an A-SE2 hydrolysis mechanism, whereas the least reactive ones have an A2 mechanism.130 Isothiocyanates are believed to hydrolyze by a mechanism that involves simultaneous proton transfer to nitrogen and attack of water at carbon in a cyclic transition... 

Figure 25. Schematic illustrating the continuous flow synthesis of 2-phenyl-l,3-dithiane [41],...

Lithio-2-phenyl-l,3-dithiane (17) has been employed in a new umpolung asymmetric addition of A-sulfinylimines, using a Lewis acid catalyst (Et2AlCl). The high (g) des obtained open up a new route to enantiopure a-amino ketones.70... 

Reactions of 2-lithio-l,3-dithiane (161) with nitroarenes gave 1,4- and 1,6-addition products whereas 2-methyl and 2-phenyl-l,3-dithiane derivatives provide only 1,6-addition products. These conjugate-addition products are transformed into the respective nitroaromatic compounds by in situ oxidation with oxygen or DDQ. In the case of 4-chloronitrobenzene, the 1,4-addition product with respect to the nitro group was mainly obtained242. A SET mechanism was proposed242, as in the case of alkyl iodides243. 

From a practical viewpoint the recently discovered vanadium-based and iron-based asymmetric sulfoxidation with hydrogen peroxide is worth mentioning [305, 306]. For vanadium, in principle as little as 0.01 mol% of catalyst can be employed (Fig. 4.111). With tridentate Schiff-bases as ligands, formed from readily available salicylaldehydes and (S)-tert-leucinol, ees of 59-70% were obtained for thioanisole [305], 85% ee for 2-phenyl-l,3-dithiane [305] and 82-91% ee for tert-butyl disulfide [307]. For iron, similar results were obtained using 4 mol% of an iron catalyst, synthesized in situ from Fe(acac)3 and the same type of Schiff base ligands as in Fig. 4.111 (see Ref. [306] for details). 

To a mixture of benzaldehyde (690 mg, 6.5 mmol) and LiBF4 (46.9 mg, 0.5 mmol) 1,3-propanedithiol (541 mg, 5.0 mmol) was added dropwise with stirring over 10 min at 25 °C under N2. After the reaction mixture was stirred at the same temperature for 1 h (completion of the reaction was checked by GC), it was directly distilled by using a Kugelrohr apparatus at 0.5 mmHg with an oven temperature of 170-200°C to give 2-phenyl-l,3-dithian (982 mg, 100%) as a white solid. 

Butyl-2-phenyl-l,3-dithianes and dithiane oxides have been synthesized with C, F, and labeling to act as probes of the GABA receptor complex <95JMC2663>. 

A good procedure for the preparation of 2-phenyl-l,3-dithiane-2-d is described by Seebach D, Erickson BW, Singh G (1966) J Org Chem 31 4303... 

V(H,H) couplings through the H—C—S—C—coupling pathway in 2-phenyl-l,3-dithiane were found to be positive by Schaefer et al RPA AMI... 

Several compounds have been prepared by nucleophilic substitution of chlorine in 2-chloro-l,3-dithian with Grignard reagent (RMgBr), malonic esters, and phenols.A mechanism for the de-ethoxycarbonylation of the 2-(l,3-dithianyl)malonates by sodium chloride or sodium ethoxide has been studied. 2-Chlorotetrahydrofuran reacts with nucleophiles such as 2-lithio-2-phenyl-l,3-dithian (326) by three simultaneous mechanisms i.e. substitution, proton abstraction, and electron transfer) to give the products (327)—(330) (Scheme 12)/° When a dithian (331 R = H or COiMe) was treated with a sulphonyl chloride in pyridine, ring-expansion to the 5//-l,4-dithiepin (332) occurred instead of the expected formation of a sulphonate. ... 

C. 3-(2-Phenyl-l,S-dithian-2-yl)indole [IH-Indole, 3-(2-phenyl-l,S- dithian-2-yiy. A solution of 24.2 g. (0.10 mole) of 2-methylthio-2-phenyl-l,3-dithiane and 6.86 g. (0.050 mole) of indole [li/-Indole] in 600 ml. of chloroform is placed in a 2-1., three-necked hask fitted with a mechanical stirrer and a 100-ml., pressure-equalizing dropping funnel. The reaction mixture is stirred vigorously, and a solution of 25 ml. (about 0.2 mole) of boron trifluoride etherate [Borane, trifluoro, compd. with l,T-oxybis[ethane](l 1)] (Note 6) in 50 ml. of chloroform is added over 10 minutes. An orange-brown, resinous precipitate forms as the slightly exothermic reaction proceeds. After a further 10 minutes of stirring, a solution of 5.86 g. (0.050 mole) of indole in 60 ml. of chloroform is added in one portion. 

Treatment of 2-lithio-2-phenyl-l,3-dithiane with 2-bromopyridine gave the substituted pyridine 44 in 50% yield . However, reaction with 2,4-dinitrobromobenzene gave none of the substitution product, but rather compound 45 resulting from oxidative dimerization of the dithiane... 

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