Sulfoxides from aldehydes

The male bean weevil sex attractant has been made by a new method of allene synthesis from aldehydes and alkenyl aryl sulfoxides by sulfoxide-metal exchange as the key reaction. 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

These trihydroxy sulfoxides are useful molecules in total synthesis because of the possible transformation of the sulfoxide into aldehyde by a Pummerer rearrangement. Homoallylic 3-hydroxy sulfoxides have also been prepared from 3-epoxy sulfoxides, readily obtained from methyl monochloroacetate (Scheme 61a). ... 

Satoh, T., Motohashi, S., Kimura, S., Tokutake, N., Yamakawa, K. The asymmetric Favorskii rearrangement a synthesis of optically active a-alkyl amides from aldehydes and (-)-l-chloroalkyl p-tolyl sulfoxide. Tetrahedron Lett. 1993, 34,4823-4826. 

The use of methyl sulfoxide as the solvent and boron trifluoride etherate as the catalyst has been explored,29 and has given good yields of acetals from aldehydes (but not ketones). The procedure does suffer from certain disadvantages, in particular, the laborious removal of the solvent by vacuum distillation, and the fact that some anomerization may result when glycosides are so treated. 

Torn et al. have utilized the asymmetric sulfoxide precursor for the synthesis of chiral propargylic alcohol (Scheme 21.15). The e.e. values of the products was greater than 99% in a few cases. The reaction of the a-carbanion derived from (irimethylsilyl)vinyl sulfoxides with aldehydes afforded a diastereomeric mixture of products R-4 and S-5. They were... 

Synthesis of aldehydes from pnmary alkyl halides or tosylales, using dimethyl sulfoxide (OMSO). 

C ( propyl) N phenylmtrone to N phenylmaleimide, 46, 96 semicarbazide hydrochloride to ami noacetone hydiochlonde, 46,1 tetraphenylcyclopentadienone to diphenyl acetylene, 46, 44 Alcohols, synthesis of equatorial, 47, 19 Aldehydes, aromatic, synthesis of, 47, 1 /3-chloro a,0 unsaturated, from ke tones and dimethylformamide-phosphorus oxy chloride, 46, 20 from alky 1 halides, 47, 97 from oxidation of alcohols with dimethyl sulfoxide, dicyclohexyl carbodumide, and pyndimum tnfluoroacetate, 47, 27 Alkylation, of 2 carbomethoxycyclo pentanone with benzyl chloride 45,7... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Carbanions formed from methyl methylthiomethyl sulfoxide 94 and ethyl ethylthio-methyl sulfoxide 95 were shown to be alkylated in excellent yields126,127. Treatment of 94 with rc-BuLi or KH and subsequent reaction with 1, n-dihalo- or bis(tosyloxy)alkane gave 3-, 4-, 5- and 6-membered 1-methylsulfmyl-l-methylthiocycloalkanes128"130. Upon hydrolyses of these products, the corresponding aldehydes and ketones are obtained. 

Demailly and coworkers195 found that the asymmetric induction increased markedly when optically active methyl pyridyl sulfoxide was treated with an aldehyde. They also synthesized (S)-chroman-2-carboxylaldehyde 152, which is the cyclic ring part of a-tocopherol, by aldol-type condensation of the optically active lithium salt of a,/3-unsaturated sulfoxide. Although the diastereomeric ratio of allylic alcohol 151 formed from lithium salt 149 and 150 was not determined, the reaction of 149 with salicylaldehyde gave the diastereomeric alcohol in a ratio of 28 72196. 

Other carbanionic groups, such as acetylide ions, and ions derived from a-methylpyridines have also been used as nucleophiles. A particularly useful nucleophile is the methylsulfinyl carbanion (CH3SOCHJ), the conjugate base of DMSO, since the P-keto sulfoxide produced can easily be reduced to a methyl ketone (p. 549). The methylsulfonyl carbanion (CH3SO2CH2 ), the conjugate base of dimethyl sulfone, behaves similarly, and the product can be similarly reduced. Certain carboxylic esters, acyl halides, and DMF acylate 1,3-dithianes (see 10-10. )2008 Qxj(jatjye hydrolysis with NBS or NCS, a-keto aldehydes or a-... 

The reaction of the aldehyde 174, prepared from D-glucose diethyl dithio-acetal by way of compounds 172 and 173, with lithium dimethyl methyl-phosphonate gave the adduct 175. Conversion of 175 into compound 176, followed by oxidation with dimethyl sulfoxide-oxalyl chloride, provided diketone 177. Cyclization of 177 with ethyldiisopropylamine gave the enone 178, which furnished compounds 179 and 180 on sodium borohydride reduction. 0-Desilylation, catalytic hydrogenation, 0-debenzyIation, and acetylation converted 179 into the pentaacetate 93 and 5a-carba-a-L-ido-pyranose pentaacetate (181). 

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