Naoshi Imaki

First Synthesis of Cotarnone, the Key Intermediate for the Synthesis of Cotarnine

Abstract The first synthesis of cotarnone (2), a degradation product of cotarnine (1), was achieved from 2-hydroxy-3-methoxy-benzaldehyde (o-vanillin), and 2 can be converted to 1 by a known method.

Preparation of 2-Methoxy-3,4-methylenedioxybenzaldehyde (Croweacin Aldehyde) from Pyrogallol

Abstract 2-Methoxy-3,4-methylenedioxybenzaldehyde (croweacin aldehyde) of high purity was prepared in 55% overall yield from pyrogallol.

Synthesis of novel ligands: two or more triphenylphosphine units containing polysilicon compounds

Abstract Novel phosphine compounds in which two or more triphenylphosphine units are introduced into a polysilicon chain have been synthesized.

An improved method for fluoro-dediazoniation of arylamines substituted with polar groups

Abstract The addition of SnX 2 (SnCl 2 or SnF 2 ), as a low redox potential reductant, at the fluoro-dediazoniation step in the deaminative fluorination of aryl amines substituted with polar groups gave high selectivities for the formation of fluoroaromatics under mild conditions. The selectivities were further increased by the addition of a nucleophilic fluoride anion source, i.e. tetrabutylammonium dihydrogen trifluoride n Bu 4 N + H 2 F 3 − , along with the reductants.

Novel phosphine-palladium complex-catalysed regioselective allylation of a Grignard reagent

Abstract The novel phosphine compounds hexamethyl-1,5-bis[p-(diphenylphosphino) phenyl] trisiloxane (1) and 2,4,6,8-tetrakis [p-(diphenylphosphino) phenyl]-2,4,6,8-tetramethylcyclotetrasiloxane (2) containing two or more triphenylphosphine units were effective as ligands in catalysts for Grignard cross-coupling. Especially the palladium complexes of cyclotetrasiloxane ligand 2 effectively catalysed the regioselective cross-coupling of allylic ethers with phenylmagnesium bromide to afford the non-terminal alkene.

Regioselective synthesis of β-bromodifluoromethyl carbonyl compounds using CF2Br2/Zn-Cu reagents

Abstract The reaction of dibromodifluoromethane with various α,β- unsaturated carbonyl compounds ( 1 ) in the presence of zinc(O) selectively gave the corresponding β-bromodifluoromethyl carbonyl compounds( 2 ) In moderate yields. No difluorocyclopropanc compounds( 3 ) were obtained. The addition of copper(l) chloride promoted the reaction. The effect of substituted groups on the α, βB-unsaturated carbonyl compounds and the mechanism of this regioselective addition reaction will be discussed.

Synthesis of Dodecatrienyl Acetate and Its Isomers. Part II

2,7-オクタジエニルアセタート〔1〕とブタジエンの反応において,ロジウム触媒の活性を増大させて酢酸ドデカトリエニルをより有利に合成することを目的として種々の検討を行なった。まずロジウム触媒におよぼす塩酸の効果を検討し,Rh1グラム原子あたり少なくともCl2グラム原子が必要であることがわかった。また反応の進行とともに触媒活性が低下していく原因のーつは2,6-オクタジエニルアセタート〔5〕および反応生成物〔2〕,〔3〕(いずれも前報に述べたn=2の非共役ジエン)による被毒であろうと推論した。さらに,反応系に四塩化炭素を存在させると触媒活性がいちじるしく増大することを見いだした(四塩化炭素は他のオレフィンとジエンのロジウム触媒反応にも有効であった)。このほかエチルアルミニウムクロリド類,およびトリメチルクロルシランもいちじるしい添加効果があった。四塩化炭素系で水素を共存させるとさらに好結果が得られた。