Alkenyl sulphoxides synthesis

Aryl-3-oxo-1 -alkenyl sulphoxides, synthesis of 282, 283 Aryloxysulphoxonium salts 941-943 synthesis of 280 Aryl radicals 879... 

Further utility of the Andersen sulphoxides synthesis is demonstrated by the preparation of optically active unsaturated sulphoxides which were first prepared by Stirling and coworkers359 from sulphinate 276 and the appropriate vinylic Grignard reagents. Later on, Posner and Tang360 prepared in a similar way a series of ( )-l-alkenyl p-tolyl sulphoxides. Posner s group accomplished also the synthesis of (+)-(S)-2-(p-tolylsulphinyl)-2-cyclopentenone 287, which is a key compound in the chiral synthesis of various natural products361 (equation 159). 

The reaction of the phenylsulphinyl allylic lithium a-carbanion 342 with oxiranes was found by Guittet and Julia to give, after rearrangement and desulphurization, dihydroxy-dienes 343427 (equation 197). Demoute and coworkers have described the alkylation reaction of a very sophisticated 2-alkenyl sulphoxide 344 as a part of the total synthesis of a juvenile hormone 345428 (equation 198). Since the allylic sulphoxide carbanion has an ambident character, the alkylation may occur sometimes also at the y-position. This direction of alkylation is observed in the case of acyclic allylic sulphoxide anions 346, and results in the formation of the corresponding allylic sulphoxide 347 and vinylic sulphoxide 348423 (equation 199). 

The carbanions of 1-alkenyl sulphoxides 400 also react with carbonyl compounds to give the corresponding condensation products384 (equation 237). Solladie and Moine have used this type of reaction in their enantiospecific synthesis of the chroman ring of a-tocopherol 401. Addition of the lithio reagent 402 to the aldehyde 403 affords the allylic alcohol 404 in 75% yield as a sole diastereoisomer481 (equation 238). 

Asymmetric synthesis based on chiral sulphoxides is a rapidly developing field. Two syntheses of (-)-raethyl jasmonate have been accomplished starting from the chiral alkenyl sulphoxide (216 Ar a... 

Van t Hoff t-factors 565 Vinylallenes rearrangement of 748 synthesis of 737 Vinyl carbonium ions 620 17a-Vinyl-17/f-hydroxysteroids, epimerization of 735 Vinyl sulphides, as alkyl sulphoxide reduction products 930, 932 Vinyl sulphones - see also Alkenyl... 

The reactions between PCI5 and alkenes or alkynes have already been discussed extensively in connection with the synthesis of a variety of phosphonic acid types (as their acid dichlorides). Successful applications have also used alkenyl alkyl sulphides (to give the dichlorides 381) to an enyne (to give the dichloride 382) and to RSC CCl (to give 383)584,585 variation of the Pummerer reaction consists in the interaction of PCI5 and a dialkyl sulphoxide, during which a trichlorophosphonium salt intermediate is decomposed with SO2 to yield a (2-alkylthioethenyl)phosphonic dichloride (Scheme 34). ... 

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