Dimethyl thio acetal

Examination of 37 basidiomycetous yeasts indicated formation of several sulfur volatiles 3-(methylthio)-l-propanol, methanethiol (MT), S-methyl thio-acetate, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), allyl methyl sulfide and 4,5-dihydro-3(2//)-thiophenone. The component produced in the largest amounts, 40 100 mg L-1, was 3-(methylthio)-l-propanol29 Cheeseripening yeasts are considered later (Section 11.1.2.4.5). 

To the ketene silyl (thio)acetal (1 equiv.) was added at room temperature neat ethyl propynoate, dimethyl acetylenedicarboxylate or etliynyl methyl ketone (1 equiv.). The mixture was stirred for 5 h at room temperature. The volatile products were removed at room temperature in vacuo (0.1 Torr) for 30 min. Purification of the crude reaction mixture by silica gel column chromatography (ethyl acetate-hexane, 5 95) afforded cycloadducts. 

Testosterone. 7a-Methyl (S-21), 7o -methylthio 17-acetate (S-119), 7o -mercapto 17-acetate (S-121), and la,7a-dimethyl 17-acetate (S-80) compared to la-methyl 17-acetate (S-72) 7a-methyl 17-ketone (S-23) compared to I7-ketone (S-22) 7a-methyl A 17a-methyl (S-138), 7a-mercapto A 17a-methyl (S-57), and 7a-acetylthio A 17a-methyl (S-58) compared to A 17a-methyl (S-15) and 7a-methyl 17a-methyl (S-20) substitutions all increase both potencies, giving rise very often to a favorable anabolic-androgenic ratio. 7a-Acetylthio 17-acetate (S-120), 7a-mercapto 17a-methyl (S-53), 7a-methylthio 17a-methyl (S-54), 7a-ethyl-thio 17a-methyl (S-55), and 7a-acetylthio 17a-methyl (S-56) substitutions cause decrease of both androgenic and anabolic potencies while maintaining a favorable anabolic-androgenic ratio. 

Further adaptations of the boranes has led to reagents which reduce carboxylic acids but afford thio-acetals rather than the aldehyde itself.Thus, with the thioborane (3 equation 1), aliphatic acids give 80-87% yields of thioacetals but aromatic acids respond less well in giving significant quantities of sulfides as well. Carboxylic acid esters are inert to this reagent but give sulfides if a Lewis acid is included. Similarly, the 1,3,2-dithiaborinane-dimethyl sulfide adduct (4 equation 2) affords cyclic dithioacetals in 70-90% isolated yields in the presence of SnCb. Aliphatic acids react in about 6 h at room temperature but aromatic acids need about 20 h and yields are somewhat poorer. This area has been reviewed.From a practical viewpoint, it should be noted that the dithiaborinane (4) requires a week for its preparation. 

Mesoionic pyrido[2,l- >][1,3]oxazines (54) afforded 4-oxo-4//-pyrido[l,2-a]pyrimidin-l-iumolates (55) and 4//-quinolizin-4-one (56) with phenyl iso(thio)cyanates [78LA1655 79CB1585 82ZN(B)222] and dimethyl acetylenedicarboxylate (79CB1585), respectively. Reaction of 2-cyano-3-methyl-lH,6//-pyridol[l,2-a][3,l]benzoxazine-l,6-dione with ammonium acetate and hydroxylamine, hydrazines, primary aliphatic or aromatic amines, and (thio)ureas gave 5-unsubstituted and 5-substituted 2-cyano-3-methyl-l//,6H-pyrido[l,2-a]quinazoline-l,6-diones (93CCC1953). 

Oxamyl (melhyl-N.N -dimethyl-N- [ (methyl-carbarn oyl)oxy] -1 -thio oxamidate) Plants including leaves, potato, tomato and wheat Ethyl acetate extraction of sample Addition of excess copper sulfate, back-titration with standard EDTA to 1 -(2-pyridylazo)2-naphthol [61]... 

Omeprazole is obtained [15] by the reaction of acetyl ethyl propionate 1 with ammonia to give ethyl -3-amino-2,3-dimethyl acrylate 2. Compound 2 was converted to to 2,4-dihydroxy-3,5,6-trimethyl pyridine 3 by treatment with methyl diethylmalonate. Treatment of compound 3 with phosphorous oxychloride produced 2,4-dichloro-3,5/6-trimethyl pyridine 4. 4-Chloro-3/5,6-trimethyl pyridine 5 was obtained by treatment of compound 4 with hydrogen. On treatment of compound 5 with hydrogen peroxide and acetic acid, 4-chloro-3,5,6-trimethyl-pyridine-N-oxide 6 was produced. Treatment of compound 6 with acetic anhydride gave 4-chloro-2-hydroxymethyl-3,5-dimethyl pyridine 7 which was converted to 2-hydroxymethyl-3,5-dimethyl-4-methoxypyridine 8 by treatment with sodium methoxide. Compound 8 was treated with thionyl chloride to produce 2-chloromethyl-3,5-dimethyl-4-methoxypyridinc 9. Compound 9 interacts with 5-methoxy-2-mercaptobenzimidazole to give 5-methoxy 2-[((4-methoxy-3,5-dimethyl-2-pyridinyl)methyl)thio]-lH-bcnzimidazole 10 which is oxidized to omeprazole 11. 

Chemical Name ethyl 2-dimethoxyphosphinothioylthio(phenyl)acetate ethyl 2-dimethoxy-thiophosphorylthio-2-phenylacetate 5-a-ethoxycarbonylbenzyl 0,0-dimethyl phosphorodithioate ethyl a-[(dimethoxy-phosphi-nothioyl)thio]benzeneacetate... 

Cava and Pollack s elegant synthesis of benzo[c]thiophene52 has been extended to the synthesis of, for example, naphtho[l,2-c]thio-phene (47),52 methyl benzo[c]thiophene-5-carboxylate,54 and 1,3-dimethyl- (48)55 and l,3,4,6-tetraphenylthieno[3,4-c]thiophene (49).56 The last compound is of particular interest because it is a remarkably stable (cf. compound 48 which only exists transiently) nonclassical thiophene containing ten n electrons for which the only uncharged resonance structure (49) contains a tetravalent sulfur atom. When the sulfoxide (50) is pyrolyzed over aluminum oxide, it gives the parent cyclic sulfide and 51 by disproportionation.57 However, when 50 is heated in acetic anhydride in the presence of iV-phenylmaleimide,... 

CARBAMIC ACID, (((((l,4-DITHIAN-2-YLIDENEAMINO)OXY)CARBONYL)METHYLAMINO )THIO)METHYL-,ETHYL ESTER see MLLIOO CARBAMC ACID, ESTER WITH SALICYLALDEHYDE DIMETHYL ACETAL see SAGIOO CARBAMIC ACID, ETHYLENEBIS(DITHIO)-, MANGANESE SALT see MAS500 CARBAMIC ACID, ETHYL ESTER see UVAOOO CARBAMIC ACID, ((4-... 

Cleavage of streptomycin with ethyl mercaptan and hydrogen chloride yielded streptidine and a new derivative of streptobiosamine, ethyl thio-streptobiosaminide hydrochloride diethyl mercaptal. Treatment of methyl streptobiosaminide hydrochloride dimethyl acetal with ethyl mercaptan and hydrogen chloride readily yielded the same mercaptal hydrochloride. It thus was apparent that the relationship between these two compounds resided simply in the replacement of methoxy by thio-ethoxy groups on the same carbon skeleton. Acetylation of the mercaptal yielded two anomeric forms of ethyl tetraacetylthiostreptobiosaminide diethyl mercaptal. ... 

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