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A short and efficient synthesis of the 1,2-dihydro-3H-pyrrolo[3,2-e]indole (2) ring system of the antitumor antibiotic CC-1065 ( 1 ) from ethyl-5-aminoindole-2-carboxylate 3 was made possible by the inherent regioselectivity of the [2,3] sigmatropic rearrangement of the azasulfonium ylide 4 and a thiation-reduction sequence for oxindole to indoline conversion.

An efficient route to the C1 to C10 fragment of the milbemycins and the avermectins has been accomplished utilizing a selenium initiated electrophilic cyclization in conjunction with a [2,3] sigmatropic selenoxide rearrangement in the key transformation.

The reductive cleavages of allyl [(phenylthio)methyl] ethers (8, 11) and an allyl [(tolylsulfonyl)methyl] ether (14) with lithium naphthalenide in THF furnish homoallylic alcohols (9, 12). The steric course of these transformations (E/Z selectivity in the case of 9, syn/anti selectivity for 12) is very similar to that of analogous Wittig-Still rearrangements.

Attempts to achieve configurational inversion of tertiary allylic alcohols by the ''classical'' approach comprising S/sub N/2-type displacement of suitable derivatives are invariably thwarted by the almost exclusive formation of allylic rearrangement and/or elimination products, nor does the diethyl azodicarboxylate-triphenylphosphine system work with tertiary substrates. Sparse reports suggest that the allyl sulfoxide-sulfenate rearrangement could be advantageously exploited to this end, although in one direction only. Illustrations on this concern are provided by the conversion of prostaglandin (13Z,15R)-PGE/sub 1/ into the 13E,15S analogue and a new route to the dihydroxyacetone side chain from a 17..cap alpha..-ethynyl-17..beta..-hydroxy steroid. In this paper it's reported (a) that an effective ''one-pot'' epimerization procedure of 17..cap alpha..-vinyl-17..beta..-hydroxy steroids to the rather inaccessible 17-epimers can be assembled by the use of the above rearrangement and (b) some stereochemical observations on this process.

The E-configurated allylic methyl ethers (I) are coupled with the α-diazocarbonyl compounds (II) in the presence of dirhodium tetraacetate to give the diastereomeric γ,δ-unsaturated α-methoxy carbonyl compounds (III) and (IV) with predominance of the erythro-isomers (III), together with the cyclopropanes (V).

Das aus dem Alkohol (I) erhaltliche Alkylierungsprodukt (III) erfahrt bei der Einwirkung von Butyl-Li eine Umlagerungsreaktion unter Bildung des homoallylischen Alkohols (IV).

Die nach Literatur dargestellten Dithioester (I) reagieren mit CzHsMgsr zu den Derivaten (II), die - mit Ausnahme von (IIc) - unter spontaner [2,3]-sigmatroper Umlagerung in die entsprechenden S-Magnesiumbromide (III) ubergehen.

La pyrolyse d'α-tosyl vinyl-2 perhydrothiolio-, -perhydrothiopyrylio- et -thiepinnioamidures conduit a la tetrahydro-2,3,7,8 tosyl-2 thiazocine-1,2 et aux homologues superieurs a 9 et 10 chainons

The asymmetric [2,3] sigmatropic rearrangement of 2-alkylamino-3-phenyl-2-pentenylmethylsulfonium methylide (4) was accomplished by reaction of ethylphenylketenimines 2, having chiral carbons next to the nitrogen atoms, with trimethylsulfonium ylide (3) and acidic hydrolysis of the imines 5 obtained led to optically active 3-methylthiomethyl-3-phenyl-2-pentanone (6). The reaction of ethylphenylketene (−)-menthylimine (2f) with 3 at −78 °C resulted in the highest optical yield (55.6%) of (R)-(−)-6 in the same sequence.

The [2,3]-sigmatropic rearrangement of a series of acetonitrile-derived allylic ammonium ylides [RCH2N+ (C4H8)-CHCN; R = 4'-t- butylcyclohexylidenemethyl (3), 4'-t-butylcyclohex-1-enyl (10), 5'-t- butyl-2'-methylcyclohex-1-enyl (14), 4'-t-butyl-2'-methylcyclohex-1- enyl (20)], followed by acid-catalysed hydrolysis in each case, furnished an excellent yield of a diastereomeric pair of β,γ-olefinic aldehydes [(5)/(6), (12)/(13), (15)/(16) and (21)/(22)]. With cyclohexylidene ylide (4) addition of the carbanion to the more exposed (equatorial vector) face is strongly preferred. In the cyclohexenyl examples there is a clear stereoelectronic requirement in opposition to steric forces which leads mainly to axial carbon-carbon bond formation.

The asymmetric [2,3] sigmatropic rearrangements of the chiral ammonium chlorides (E)-(3a,b) were achieved upon treatment with t-BuOK followed by acidic hydrolysis of the aminonitriles (5a,b) obtained to give (R)-(+)-2-methyl-2-phenyl-3-butenal (6). The rearrangement of (E)-(3a) at −78° resulted in the highest optical yield (90%) of (R)-(+)-(6). The geometrical isomer (Z)-(3a) underwent the same [2,3] shift under the same conditions to afford (S)-(−)-(6). The mechanism of this asymmetric induction is discussed based on these results.

Addition of N-nitrenes to allyl aryl sulphides gives N-(heterocyclic)sulphenamides by [2,3]sigmatropic rearrangement of the initially formed sulphilimines.

The cycloaddition reaction of 2,4-dinitrophenylsulfinylpropadiene with several nitrones has been investigated. The initial 3+2-cycloadduct readily undergoes a subsequent 2,3-sigmatropic rearrangement.

Rhodium catalyzed reaction of 4-methoxy-6-phenylthiomethyl-2-pyrone with dimethyldiazomalonate affords 5-(bis(methoxycarbonyl))(phenylthio)methyl-4-methoxy-6-methylene-5,6- -dihydro-2-pyrone via [2,3]sigmatropic rearrangement of the corresponding sulphur ylide. Cyclopropanation of the 6-methylene double bond occurs by the less hindered side. © 1986., Financial support from CAICYT (Ministerio de Educación y Ciencia of Spain. Project 2014/83) is gratefully acknowledged.

Reaction of allyl aryl sulfides and α-diazoacetic acid esters in the presence of optically active Co(III)-salen complex (8-Br) provided 3-substituted 2-arylthio-4-pentenoic acid esters stereoselectively by way of enantioselective S-ylide formation and subsequent diastereoselective [2,3]sigmatropic rearrangement. For example, the reaction of cinnamyl phenyl sulfide and (−)-menthyl α-diazoacetate provided (−)-menthyl (2R,3S)-2-phenylthio-3-phenyl-4-pentenoate of 74% de preferentially.

Thermolysis of the sodium salts of S-allyl-S′-methyldithiocarbonate tosylhydrazones (4) followed by methylation provided good yields of the corresponding 1,1-bis(methylthio)-1,3-butadiene (1) via the [2,3]sigmatropic rearrangement of the dithiocarbenes(5).

a one-step conversion of butyne-1,4-diol (1) to 2,3-di(phenylsulfinyl)-1,3-butadiene (4) and the conversion of this bis-sulfoxide to the sulfoxide-sulfone 6 and the bis-sulfone 5 are reported.