3.4- Dimethyl-l,2-dithiolane

Dimethyl-l,2- dithiolane Ferret AGS Red fox feces Rat Vernet-Mauryeta/., 1984... 

Similarly, two sulfur compounds from predators, 3,3-dimethyl-l,2-dithiolane and (E)-(Z)-2,4,5-trimethyl-A -thiazoline had no effect on wild roof rats, Rattus rattus, in a Hawaiian macadamia orchard (Burwash etal, 1998). 

The responses of gophers to the weasel mixture and single anal gland compounds are illustrated in Figure 3. There was no difference in responses between males and females in these trials. Gophers clearly avoided the 2-propylthietane, polymerized 3-propyl-l,2-dithiolane, and the weasel mixture. They also tended to avoid the 3,3-dimethyl-l,2-dithiolane from the ferret with the following results from 3 trials (control vs. treatment) 14-9 14-9 8-1. The control test, fresh 3-propyl-l,2-dithiolane, and 2-methylthiophene (novel odor) had little effect on gopher behavior. 

Fig. 4. Responses of pocket gophers to mustelid anal gland compounds in the field at Vernon study area. 3PDIT = 3-propyl-l,2-dithiolane. DMDI 3,3-dimethyl-l,2-dithiolane. p < 0.05 significant difference by chi-square. 

Schildknecht et al. had previously found both 14 and 15 in mink scent, but they had also reported finding 3,3-dimethyl-l,2 dithiolane Xo find 16. 

Ferrets, Mustek furo, distinguish between anal sac secretions of males and females. Males did not discriminate between the anal gland odors of estrous and anestrous females. Chemical sex differences were found, but no seasonal differences. Males had high concentrations of 2,3-dimethylthietane and/or 3,4-dimethyl-l,2-dithiolane (Fig. 7.6). Most individuals had 2-propylthietane. Clapperton etal. (1988) concluded that the odor of the anal gland provides sexual and territorial signals and cues to individual identity. 

As the final pH of meat increases above the normal range of 5.6-5.8, there is a decrease in meat flavour.101102 The reaction between norfuraneol and cysteine, which plays a crucial role in meat flavour, is very sensitive to pH.103 At pH 4.5, the major volatile products are mercaptoketones, furan- and thiophenethiols, 2-methyltetra-hydrothiophenone, and 3,5-dimethyl-l,2-dithiolan-4-one, whereas, at pH 6.5, these compounds were detected, if at all, only in traces, except for the thiophenone however, pyrroles, pyrazines, thiazoles, and oxazoles had achieved prominence. The sensory observations are a clear reflection of such differences. Similar effects of pH had been found for the ribose-cysteine and other systems.104... 

C. (E)-3,3-Dimethyl-l-phenyl-1 -butene. In a 1-L, two-necked, round-bottomed flask fitted with a reflux condenser, rubber septum, and a magnetic stirring bar are placed 17.8 g (0.08 mol) of 2-methyl-2-(2-phenylethenyl)-1,3-dithiolane and 2.17 g (0.004 mol) of [1,3-bis(diphenylphosphino)propane]nickel(ll) chloride [NiCl2(dppp)] (Note 5). The flask is evacuated and flushed with nitrogen three times. To the above mixture is added 300 mL of anhydrous tetrahydrofuran (Note 6). The ether solution of methylmagnesium iodide prepared in Step B is introduced with a double-ended needle in one portion (Note 7). The mixture is heated under reflux for 24 hr, cooled to room temperature, and treated with 200 mL of saturated ammonium chloride solution. 

The structures were confirmed by synthesis. Among the most original compounds figure homokahweo-furan (2,4-dimethyl-3-oxa-8-thiabicyclo[3.3.0]-l,4-octadiene), a homologue of the typical kahweofuran identified by Stoll et al. (1967), 3,3-dimethyl-1,2-dithiolane and 3,3-dimethyl-4-oxo-l,2-dithiolane. 

Cyclic Disulphides and Cyclic Diselenides.—Formation. No fundamentally new methods of synthesis of this class of compounds have been reported in the past two years. For l,2>dithiolan the oxidation of l,3>dithiols remains a favoured method, the use of iodine in the presence of triethylamine leading smoothly to 1,2-dithiolans without attendant polymerization. cis- and tra/ -l,2-Dithiolan-3,5-dicarboxylic acids were prepared from a diastereo-isomeric mixture of dimethyl 2,4-dibromoglutarates by sequential treatment with potassium thioacetate and potassium hydroxide in the presence of iodine,and jyn-2,3-dithiabicyclo[3,2,l]octan-8-ol was formed from 2,6-dibromocyclohexanone by successive treatment with potassium thiocyanate, lithium aluminium hydride, and iodine. The stereoselective formation of the less thermodynamically stable alcohol in this case was attributed partly to the formation of chelates with sulphur-aluminium bonds. 2,2-Dimethyl-l,3-dibromopropane was converted into 4,4-dimethyl-l,2-diselenolan on treatment with potassium selenocyanate at 175 °C, but at 140 °C the product was 3,3-dimethylselenetan. Reductive debenzylation of 2-alkylamino-l,3-bis(benzylthio)propanes with lithium in liquid ammonia and oxidation of the resultant dithiols with air afforded 4-dialkylamino-l,2-dithiolans, whilst treatment of a-bromomethyl-chalcone with sodium hydrosulphide gave, as minor product, trans-3 phenyl-4-benzoyl-l,2-dithiolan. Among the many products of thermal decomposition of /ra/ -2,4-diphenylthietan was l,4,5,7-tetraphenyl-2,3-dithiabicyclo [2,2,2]octane. ... 

Number ( (2,4-dimethyl-l,3-dithiolan-2- yl)methylene)aniiiio)- pounds pounds... 

Literature on the stability of individual cydk disulfides covers (i) compounds that polymerize on standing like 3,3-dimethyl-1 -dithiolaiK [124,12, 3-hydroxy-l,2-dithiolane [126] and iV-phenyl-4-oxo-5-aza-l,2-dithia-cyclohexane [127,128] ii) compoimds which polymerizes on heating such as dibenzo-lA5,6-tetrathiocin [129] and iii) compounds that polymeixK in neat form when a catalyst is added, such as cis-l,2-dithiacyclohex-4-aie [130] and l-oxa-4,5-dithiacycloheptane [13, 119, 130]. Detailed study of the stability of cyclic disulfides towards polymerization revealed that 1,2-dithiai are the only class of simple cyclic disulfides that is thermodynamically staUe with respect to its polymerization in the melt or as concentrated solutions [131]. 

Animal Sources. The marine annelid worm Lumbrineris hetero-poda produces an insect toxin nereistoxin, 24, 4-N,N-dimethyl-amino-1,2-dithiolane (5 ). The mink MusteXa vison) affords 2,2-dimethylthietane, 14, and 3,3-dimethy1-1,2-dithiolane, 25 (28,63, 64), the ferret Musteta putoris) secretes 14, 25, cis- and trans-2,3-dimethylthietane, 2-propyl- and 2-pentyl-thietane, cis and trans-3,4-dimethyl-l,2-dithiolane, and 3-propyl-l,2-dithiolane (65), and the stoat (Mustela erminea) contains 2-ethyl-, 2-propyl-, and 2-pentyl-thietane, and 3-ethyl- and 3-propyl-l,2-dithiolane in its anal gland (5, ). These several thiaheterocycles from mustela species probably function as scent markers. 

A [5 - 2 + 2 + 1] fragmentation followed by cyclization forming a new five-membered ring was observed by FVP studies of 2-propenyl-l,3-dithiolan 1,1-dioxide (79) (95H1967). The reaction mixture consists of four products thiophene (26%), 2,5-dihydrothiophene (80,34%), 4-methyl-2-propenyI-4//-l,3-dithiine (20%), and 2,6-dimethyl-2//,6//-l,5-dithiocine (20%). The last two compounds are formed by [4 + 2] or [4 + 4] dimerization of the intermediate 2-butenethial. Formation of 80 involves a 1,5-H shift of the as-butenethial, followed by cyclization. 

Related reactions involve the alkylation, allylation or tenzylation of (i) a,a-di(Aio)alkylmagnesium halides, resulting from the thiophilic addition of Grignard reagents on dithioesters (Scheme 55, entry 5).259.260 (li) 2-lithio-l,3-benzodithioles (Scheme 55, entry d) " (iii) 2-aryl-2-lithio-l,3-dithiolanes and 2-lithio-l,3-dithianes derived from die l,2-dimethyl-4,5-di(mercapto)methylbenzene (Scheme 55, entry c) ( 3,264... 

Dioxolane formation by acid-catalyzed exchange between 2,2-dimethyl-l,3-dioxolane (DMD) and a ketone in an inert (nonpolar) solvent, or simply in excess DMD, requires 4 to 7 h under classical conditions [176]. This reaction is readily achieved under microwave irradiation in high yields within 4 to 30 min (Scheme 10.91) [174]. It has been shown that yields are higher under the action of micro-waves. This dioxolane exchange was subsequently scaled up to 250 g in the Synthe-wave 1000 with the same yields [177] and this type of carbonyl protection was extended to dithiolanes and oxathiolanes [178]. 

Dithioacetals, 1,3-dithianes or 13-dithiolanes are prepared by reaction of the corresponding carbonyl compound in the presence of an acid catalyst (cone. HQ, Lewis acids such as Znh, BFs EtaO, TMS-Cl, etc.) with a thiol or dithiol. Silica gel treated with thionyl chloride was found to be an effective as well as selective catalyst for thioacetalization of aldehydes. Thioacetalization can also be achieved using a (polystyryl)diphenylphosphine-4odine complex as a catalyst Conversion of aldehydes or acetals into 1,3-dithianes is achieved with the aid of organotin thioalkoxides and organotin triflates or with 2,2-di-methyl-2-sila-l,3-dithiane. Direct conversion of carboxylic acids to 1,3-dithianes can be carried out by reaction with 1,3,2-dithiabomenane-dimethyl sulfide and tin(II) chloride or 1,3,2-dithiaborolene with trichloromethyllithium followed by basic hydrolysis. 

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