Hisahiro Hagiwara

Facile preparation of thiocarbonylimidazolide by organic solid state reaction

Abstract Thiocarbonylimidazolide 3 has been prepared from alcohol 1 and thiocarbonyldiimidazole 2 by grinding both substrates with pestle and mortar.

Revision of the structure of raphanusanins, phototropism-regulating substances of radish hypocotyls

Abstract The structures of raphanusanins A and B, growth inhibitors involved in phototropism of radish hypocotyls, were determined by X-ray crystallographic structure analysis and by spectral studies to be (3R*,6R*)- and (3R*,6S*)-3-[methoxy(methylthio)methyl]-2-pyrrolidinethione, respectively. Therefore, the previously proposed structure of these compounds of 2-piperidinethione skeleton should be revised.

High diastereoselection in the aldol reaction of the bistrimethylsilyl enol ether of methyl acetoacetate with 2-benzyloxyhexanal: synthesis of (–)-pestalotin

Aldol condensation of the bistrimethylsilyl enol ether of methyl acetoacetate, compound 2, with 2-benzyloxyhexanal 3c affords highly selectively (99:1) the syn-aldol adduct 4c in the presence of titanium tetrachloride. The stereocontrolled synthesis of (–)-pestalotin 7 has been achieved.

Organic Reaction Without Solvent. Efficient Synthesis of Thiocarbonylimidazolide

Abstract Thiocarbonylimidazolide has been prepared from thiocarbonyl-diimidazole and alcohol simply by grinding in a mortar at ambient temperature.

Double Michael reaction of Wieland-Miescher ketone

Abstract Enolate of Wieland-Miescher ketone 1 has reacted with methyl acrylate to give methyl (1S*,2S*,4R*,6S*)-6-methyltricyclo[6.2.2.0 1,6]-dodecan-7, 12-dion-2-carboxylate 5 whose structure has been determined by X-ray crystallography after transformation of 5 into sultamamide 8a.

Direct 1,4-addition of aldehydes to vinylketones

Abstract Aldehydes directly add in 1,4-manner to vinylketones in the presence of 0.5 eq. of diethylaminotrimethylsilane without a solvent to give 5-ketoaldehydes.

Revision of the structure of raphanusamide, a phototropism-regulating substance of radish hypocotyls

Abstract The structure of raphanusamide, a growth inhibitor involved in phototropism of radish hypocotyls, was determined to be 3-( E )-methoxymethylene-2-pyrrolidinethione by X-ray crystallographic structure analysis.

Enantioselective syntheses of (−)-7-oxo-kolavenic acid and (−)-methyl solidagonate from (−)-verbenone

Abstract The first enantioselective synthesis of the title neo-trans-clerodanes 3 and 4b from (−)-verbenone 5 has been accomplished using the ene reaction and stereoselective conjugate addition reaction to the enone 13 as the key step.

Total synthesis of (+)-compactin by a double Michael protocol

The total synthesis of (+)-compactin 1 has been achieved by employing a double Michael reaction of (R)-1-acetyl-3-(tert-butyldimethylsiloxy)cyclohexene 16 with methyl crotonate as the key reaction.

Annulation by sequential double Michael reaction; synthesis of decalones and its application to the syntheses of ε-cadinene, khusitone and khusilal

Reaction of the kinetic enolates or the trimethylsilyl enol ethers of 1-acetylcyclohexenes with α,β-unsaturated carbonyl compounds affords 4-substituted 1 -decalone derivatives under basic or Lewis acidic conditions. The reaction with acrylates of chiral alcohols has achieved 70% diastereoselection. Application of these reactions has enabled syntheses of Iµ-cadinene, khusitone and khusilal to be accomplished.