5.5- Dimethyl dithiocarbonate

An unusual reaction of methoxythiocarbonyl chloride with tetra-n-butylammo-nium iodide in the presence of sodium thiosulphate leads to the formation of 0,5-dimethyl dithiocarbonate [49], The reaction appears to involve a reduction step, with the iodide anion being regenerated from the released iodine by the thiosulphate ions (Scheme 4.7). In the absence of the thiosulphate ions, the thiocarbonyl chloride decomposes to yield chloromethane and carbonyl sulphide. 

Minkwitz and co-workers have recently obtained the X-ray crystal structure of protonated thiocarbonic acid, protonated (9,5-dimethyl dithiocarbonate, and protonated dimethyl trithiocarbonate. Protonated thiocarbonic acid 354 has C—S bond lengths of 1.683-1.708 A.662 The small differences imply a nonequal distribution of the positive charge over the S atoms. All hydrogen atoms have trans positions and they are... 

Procedures employing phosgene equivalents can also be applied to the large-scale preparations of those carbamates, ureas, or heterocyclic compounds that are difficult to synthesize efficiently by other and safer methods, mainly compounds bearing different functionalities and incorporating chiral carbons in the side chains. In this regard, a first crucial step towards more environmentally friendly approaches to ureas was taken with the use of bis(4-nitrophenyl)carbonate, S,S-dimethyl-dithiocarbonate, 1,1-carbonyl-bis(imidazole), di-tert-butyl dicarbonate, and phenyl chloroformate [28],... 

Bis-thioesters undergo smooth Dieckmann cyclizations [NaH EtSH(cat.), (MeOCH2)2, 2—6 h, 20 °C] to give cyclic j8-keto-thioesters. As with the oxygen analogues, only five- or six-membered rings can be efficiently prepared in this way. Decarboxylation occurs on desulphurization with W2 Raney nickel (EtOH, 20 °C). j8-Keto-thioesters are also available by treatment of ketone enolates with excess S,5 -dimethyl dithiocarbonate " they can also be alkylated in much the same way as jS-keto-esters. ... 

Quebrachitol was converted into iL-c/j/roinositol (105). Exhaustive O-isopropylidenation of 105 with 2,2-dimethoxypropane, selective removal of the 3,4-0-protective group, and preferential 3-0-benzylation gave compound 106. Oxidation of 106 with dimethyl sulfoxide-oxalyl chloride provided the inosose 107. Wittig reaction of 107 with methyl(triphenyl)phos-phonium bromide and butyllithium, and subsequent hydroboration and oxidation furnished compound 108. A series of reactions, namely, protection of the primary hydroxyl group, 0-debenzylation, formation of A-methyl dithiocarbonate, deoxygenation with tributyltin hydride, and removal of the protective groups, converted 108 into 7. 

The guanidine moiety was incorporated by dimethyl (2,2,5,7,8-pentamethylchromane-6-sulfonyl N-alkylated amino) dithiocarbonate[264] (Pmc-dithiocarbonate) 91 in two steps. One methylsulfanyl group was replaced by the primary amino group of Bzl-Norn-OBzl in the presence of excess DIPEA and the isothiourea obtained was reacted with silver nitrate under basic conditions to yield the intermediate sulfonylcarbodiimide which reacts immediately with ammonia to yield the guanidine Bzl-Narg(Pmc)-OBzl 91. 

Another method involves anionic cycloaddition of triethylammonium salts of dithioacids or dithiocarbonates to dimethyl acetylenedicarboxylate to produce the 1,3-dithioles (302) (81ZOR1788, 80ZOR2616). Also dithiocarboxylic esters react with dimethyl acetylenedicarboxylate giving substituted 1,3-dithioles (303) (80ZOR2047,79ZOR1106). 

In the study of amidyl radicals, obtained from Ar-amidosulfonyl radicals by extmsion of sulfur dioxide, sulfonamide 187 reacted with S -( 1,1 -dimethyl-3-oxobutyl) O-ethyl dithiocarbonate to give, as minor product, the thiazocinone 188 via cyclization of the Ar-amido sulfonyl radical. The major product (55%) was the corresponding seven-membered azepinone from the cyclization of the amidyl radical (Equation 14) <2004CC1848>. 

To a suspension of 23 mg (10 mmol) of sodium sand in benzene is added 1.26 g (10 mmol) of cis-3,5-dimethyl-2-cyclohexenol and the suspension refluxed with stirring. After the metal has completely reacted 0.9 g (12 mmol) of carbon disulfide is added with ice-cooling and the mixture is stirred for 2 h at r.t. and then 1.25 g (10 mmol) of CH3I is added. After stirring overnight, the mixture is filtered, washed with H20 and dried over Na,S04. The filtrate is concentrated under reduced pressure and the residue is distilled to give the pure dithiocarbonate yield 59% bp 104CC/1 Torr. 

OPSi2C,H27, Phosphine, [2,2-dimethyl-1-(trimethylsiloxy)propylidene](tri-methylsilyl)-, 27 250 OS2CH, Dithiocarbonic acid, 27 287 OSiC4H 2, Silane, methoxytrimethyl-,... 

Methyl phthalate, see Dimethyl phthalate 2-(l-Methylpropyl)-4,6-dinitrophenol, see Dinoseb 6-Methyl-2,3-quinoxaline dithiocarbonate, see Quinomethionate 6-Methyl-2,3-quinoxalinedithiol cyclic carbonate, see Quinomethionate 6-Methyl-2,3-quinoxalinedithiol cyclic dithiocaibonate, see Quinomethionate... 

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