Sodium methoxide sulfoxide

Similarly sodium methoxide (NaOCHj) is a suitable base and is used m methyl alco hoi Potassium hydroxide m ethyl alcohol is another base-solvent combination often employed m the dehydrohalogenation of alkyl halides Potassium tert butoxide [K0C(CH3)3] is the preferred base when the alkyl halide is primary it is used m either tert butyl alcohol or dimethyl sulfoxide as solvent... 

Starting from l.l-dichloro-7b-ethoxy-2-methyl-1,1 a,2,7-tetrahydrobenzo[/)]cyclopropa[prepared from the corresponding benzothiopyran by addition of dichlorocarbene, the three 1-benzothiepins 6a-c are formed upon treatment with strong bases, i.e. sodium methoxide or ethoxide in dimethyl sulfoxide.73 The optimal yield of each 1-benzo-thiepin compound depends on the molar equivalents of base, as follows from different ring-opening mechanisms. 

Though the PECH decomposes to indefinite fragments with n-butyl lithium or sodium hydride in THF at room temperature, it reacts with sodium methoxide with liberation of Cl in which the -elimination of hydrogen chloride predominates instead of nucleophilic substitution. For instance, PECH in DMSO was reacted with double the molar quantity of sodium methoxide at room temperature for 24 h to give the unsaturated polyether (DS 92.3%,v(C=C) 1630,5 (=CH2) 795 cm" ) after purification by dissolution(DMF)-precipitation (H20) technique. A similar unsaturated polyther was obtained by the pyrolysis of the sulfilimine 13 (110-130°C) but not of sulfoxide 12 (100-150°C). When the polymer 26, was heated to 90°C, the absorption of C=C and =CH2 decreased and a new absorption at 1720 cm appeared and increased. This is explained as a result of [3.3] sigmatropic rearrangement of to afford including C=CH2 and C=0 structure as shown in equation 7. 

In the Michael addition reaction depicted in eq. [146] the diastereomeric sulfoxides 312 are formed under kinetic control conditions, therefore, the addition of sodium diethyl malonate is an irreversible process. On the contrary, addition of sodium methoxide to the sulfoxide 311 is a thermodynamically controlled process and leads to a mixture of diastereomeric ]3-methoxysulfoxides 313 in a 31 69 ratio (320). 

Phenolannelation. Methyl vinyl ketone (and substituted vinyl ketones) undergo Robinson annelation with the /(-keto sulfoxide (1) to afford the 5,6,7,8-tetrahydro-2-naphthol (2) with loss of hcn/cnesnlfenic acid. Sodium methoxide is used as base, and the reaction proceeds at 0 - 25°. 

Protecting groups were removed by treatment of the polymer with sodium methoxide in p-dioxane, followed by tetraethylammonium hydroxide. Although nitrogen-free polymers were obtained by this procedure, the polymers had suffered a 16-20% decrease in PH. The resulting polymers were insoluble in water, sodium hydroxide, N, -dimethylformamide, and methyl sulfoxide, but were soluble in tetraethylammonium hydroxide and in Schweizer reagent. 

Methylene triphenylarsorane (//, 31, 34, 39) has been prepared in situ from the salt in ether (34, 39), benzene (34, 39, 60), tetrahydrofuran (31), or dimethyl sulfoxide (II) by reaction with butyl- or phenyllithium (34, 39), sodium hydride (31), methylsulfinylcarbanion (II), or sodamide (102). Ethylidene triphenylarsorane has been prepared by reaction with methylsulfinylcarbanion (II) whereas fluorenylidene-(9)-trimethyl- and fluor-enylidene-(9)-dimethylbenzylarsorane (101) have been made using phenyllithium in ether. Sodium methoxide in methanol has been used successfully (41, 47, 48, 94) to generate ylides from their corresponding salts when R is an electron-withdrawing group (e.g., COOR, COR, or CN). 

Johnson, Nalley, Wei dig, and Arfan (50) have investigated the stereochemistry of the reaction of sodium methoxide with the isomeric 0-alkylbenzo-hydroximoyl chloride 227 and 230 in dimethyl sulfoxide-methanol (9 1). They found that 227 gave almost exclusively the Z-isomer 229 while 230 gave a mixture of Z and isomers 229 and 233 where the isomer largely predominates. 

The phenyl 1-thioparatoside 145 was activated with TV-iodosuccinimide and silver triflate and reacted with a convenient derivative of the disaccharide (1-d-GalpNAc-(l ->4)-p-D-GlcpNAc. After removal of the pivaloyl-protecting group with sodium methoxide, isomerization of paratose to tyvelose was performed in a one-pot reaction by oxidation with dimethyl sulfoxide and acetic anhydride, followed by reduction with L-Selectride. Selectivity of the reduction was better... 

More recently a third type of orthoester was produced (51) (Scheme 5). Germine (2) was treated with triethyl orthoacetate and p-toluenesulfonic acid in dimethyl sulfoxide (DMSO) to give neogermine B/C-orthoacetate (21) which could be isomerized with sodium methoxide at room temperature to the isogermine derivative (22). Similarly, germine-3,16-diacetate (7)... 

Reaction of Methyl 4,6-0-Benzylidene-3-C-methyl-2-0-p-tolylsulfonyI-a-D-allo-pyranoside with Sodium Methoxide in Methyl Sulfoxide Synthesis of 6-Deoxy-3-C-methyl-3-O-methyl-D-allose (2-Hydroxy-D-cladinose), G. B. Howarth, W. A. Szarek, and J. K. N. Jones, Carbohydr. Res., 11 (1969) 257-262. 

Amino-5-chloro-3-hydrazinocarbonylpyrazine with S-methylthiourea hy-driodide and sodium methoxide in dimethyl sulfoxide at 100° gave 2-amino-5-chloro-... 

They can also be used as vinylic carbanion species as shown by the asymmetric synthesis of the chro-man ring of vitamin The (E)/(Z) mixture of chiral sulfoxide (9) was readily isomerized into the ( )-isomer with LDA in THF (the exclusive formation of the ( )-isomer was due to the chelation of lithium with an oxygen of the acetal). Condensation to trimethylhydroquinonecarbaldehyde gave only one diastereoisomer and then the cyclization in presence of sodium methoxide was also fully stereoselective (the stereochemistry of the cyclization being controlled by that of the allylic hydroxy group which is eliminated during the cyclization Scheme 48). 

Alternative methods include deprotonation of the amine, to enhance its nucleophilicity, by one equivalent of sodium methoxide, sodium amide, metallic sodium,n-butyllithium, sodium hydride in dimethyl sulfoxide or Grignard reagent. Under less drastic basic conditions 2-hydroxypyridine catalyzes the reaction at elevated temperatures (130-170 °C). ... 

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