Hiroshi Nakatani

Ruthenium-catalysed atom-transfer cyclisation of N-(cyclohex-2-enyl)-α-chloro-α-(phenylthio)acetamides. A formal total synthesis of (±)-haemanthidine and (±)-pretazettine

The hydroindole (18), which previously served as a key intemediate in the total synthesis of (±)-haemanthidine (2) and (±)-pretazettine (1), has been prepared in a highly stereocontrolled manner by a reaction sequence involving a ruthenium-catalysed atom-transfer cyclisation of an α-chloro sulphide.

A [2++4] polar cycloaddition of α-chlorosulfides with conjugated dienes: one-pot synthesis of 1-acyl- and 1-cyano-1-methylthio-2-vinylcyclopropanes

Abstract In the presence of SnCl 4 , methoxycarbonyl-, acetyl-, benzoyl-, or cyano-substituted chloromethyl methyl sulfide (1–4) undergoes [2 + +4] polar cycloaddition with conjugated dienes to afford the cycloadducts of type 7, which, on treatment with base, are converted into the 1-acyl- or 1-cyano-1-methylthio-2-vinylcyclopropanes 9–10 via the ylide intermediates of type 8.

Introduction of an arylthio(trimethylsilyl)methyl group into arenes by Friedel-Crafts reaction: synthesis of arylmethyltrimethylsilanes

Abstract Friedel-crafts reactions of [arylthio(chloro)methyl]trimethylsilanes (1a,b) with arenes gave [aryl(arylthio)methyl]trimethylsilanes (2a,b), which were converted into arylmethyltrimethylsilanes (3) by reduction with raney nickel.

A short synthesis of (±)-cuparene

Lewis-acid-promoted reaction of m-tolylthiomethyl chloride (1) with 1,2-dimethylcyclopentene (2) followed by desulphurisation of the resultant [4++ 2] cycloadduct (4) gives (±)-cuparene (5).

A [2++ 4] polar cycloaddition of α-thiocarbocations with 1,3-dienes: synthesis and thermal reaction of 1-acyl-1-methylthio-2-vinylcyclopropanes

Treatment of methyl 2-chloro-2-(methylthio)acetate, 1-chloro-1-(methylthio)propan-2-one, chloro-(methylthio)methyl phenyl ketone, or 2-chloro-2-(methylthio)acetonitrile with 1,3-dienes in the presence of stannic chloride followed by addition of triethylamine gave 1-acyl- or 1-cyano-1-(methylthio)-2-vinylcyclopropanes. A mechanistic interpretation of this reaction is presented. Thermal behaviour of the vinylcyclopropanes is also described.

Desilylative Pummerer-like rearrangement of α-trimethylsilyl-substituted sulphoxides and sulphides: formation of α-acyloxy and α-halogeno sulphides

α-Trimethylsilyl-substituted sulphoxides and sulphides undergo rearrangement with loss of the silyl group when treated respectively with trifluoroacetic anhydride and with N-halogenosuccinimide in the presence of trifluoroacetic acid, giving α-acyloxy sulphides and α-halogeno sulphides.

Reaction of [arylthio(chloro)methyl]trimethylsilanes with arenes and alk-1-enes in the presence of Lewis acid: syntheses of [aryl(arylthio)methyl]- and (1-arylthioalk-3-enyl)-trimethylsilanes

Treatment of equimolar amounts of the [arylthio(chloro)methyl) trimethylsilanes (2) or (3) and electron-rich arenes with an equimolar amount of Lewis acid (SnCI4 or TiCI4) gave the Friedel-Crafts reaction products, [aryl (arylthio)methyl] trimethylsilanes (4) or (5), in high yields. Similar treatment of the chlorides (2) or (3) with alk-1-enes gave ene type products, (1-arylthioalk-3-enyl]trimethylsilanes (12) or (13), in moderate yields. Some chemical transformations of these products are also described.

A new synthesis of vinyl sulphides by Lewis acid promoted reaction of [chloro-(arylthio)methyl]trimethylsilanes with trisubstituted alkenes

Treatment of the α-chloro-α-silyl sulphides (1) or (5) with trisubstituted alkenes (6) in the presence of SnCl4 gave the vinyl sulphides (7) or (8), the formation of which involves a carbenium ion rearrangement controlled by the silyl group.