Sulphoxides alkenyl

Generation of anions a to the sulphinyl group takes place also in 1 -alkenyl sulphoxides and can easily be achieved by using such bases as LDA383-385, t-BuLi386 and n-BuLi (for allenyl sulphoxides)387. 

As mentioned above, 1-alkenyl aryl sulphoxides can effectively be a-lithiated by treatment with a slight excess of LDA in THF at — 78°. The 1-(arylsulphinyl)alkenyllithium reagents 331 so generated react cleanly and rapidly with a variety of electrophiles to give 1-substituted 1-alkenyl sulphoxides 332 in high yields (equation 191). 

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). 

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

Sulphonylthioureas, mass spectra of 158 Sulphoxides - see also Alkoxysulphoxides, Aminosulphoxides, -Anilinosulphoxides, Cyanosulphoxides, a, /i-Dihalosulphoxides, Disulphoxides, Enaminosulphoxides, Episulphoxides, Epoxysulphoxides, Halosulphoxides, Hydroxysulphoxides, /i-Iminosulphoxides, Ketosulphoxides, a-Lithiosulphoxides, /i-Oximinosulphoxides, Persulphoxides, a-Thioamidosulphoxides addition reaction of 619-623, 836-845 aliphatic - see Aliphatic sulphoxides alkenyl - see Alkenyl sulphoxides alkyl aryl - see Alkyl aryl sulphoxides /(-alkylthio(arylthio)ethyl - see /J-Alkylthio(arylthio)ethyl sulphoxides... 

Alkylation of the sulphone (111) with Bu"Li-Me3SiCH2l gave the /8-silyl-sulphone (112) which with Bu NF gave ° 3-methylene-5a-cholestane (113). Alkenyl sulphoxides, such as (114), were reduced to the alkenyl sulphides, without double-bond isomerization, using EtNlgBr-Cul " and the terminal allene (115) was prepared by treatment of (114) with LTMP. Reaction of... 

The participation of alkenyl sulphoxides in Michael and related additions continues to attract interest.264 Posner has reported on the addition of ester and ketone enolates to enantiomerically pure (268) and (269).265... 

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... 

Although alkenyl sulphoxides are well established as Diels-Alder dienophiles, this year has seen the first effective use of a sul-phinyl diene (221 Ar d U-MeC Hn) as a chiral enophile in an inverse electron demand cycloaddition reaction. °... 

PhS(0)(0Ph)Me + RLi and LiX - PhSOCH X + PhSO Me]/ or reduction with homologation (with RjCuLi and LiX)/ Standard sulphinylation procedures reported include electrophilic substitution of phenols with ArSOCl and AlClj and the preparation of optically active sulphoxides from resolved (—)-menthyl sulphinates with ( )-l-alkenylmagnesium bromides or arylthiomethyl- or arylsulphonylmethyl-lithium compounds/ A practical route to 1-alkenyl sulphoxides uses non-activated alkynes and sulphenic acids, generated in situ from the thermolysis of 2-cyanoethyl phenyl sulphoxides/ ... 

Conjugate addition of lithium dimethylcuprate to the optically pure a-(methoxycarbonyl)alkenyl sulphoxide (8), followed by reduction and saponification, gives (R )-(+)-3-methylnonanoic acid (9) (Scheme 8). The utility of this scheme clearly depends on the accessibility of the required optically active sulphoxides. 

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