Makoto Okawara

General synthetic route to γ-butyrolactones via stereoselective radical cyclization by organotin species

A new method for the preparation of γ-butyrolactones is described in which the key step is the highly stereoselective radical cyclization of bromoacetals to 2-alkoxytetrahydrofurans in the presence of polymeric or low-molecular weight organotin species. 2-Alkoxytetrahydrofurans can be easily converted into γ-butyrolactones by Jones oxidation.

Synthesis of (±)-lavandulol and its related homoallylic alcohol via allyl transfer from sulphur to tin

(±)-Lavandulol and related homoallylic alcohols were prepared by the stannolysis of allylic sulphones and the subsequent hydroxymethylation of the resulting allylic stannanes with trioxan–BF3·OEt2.

Radical cyclization of unsaturated α-sulphonyl radicals. Preparation and stereochemistry of arylsulphonyl-tetrahydrofuran and -pyrrolidine

1-Bromo-1-p-tolylsulphonyl-2-allyloxyethane derivatives (2) reacted with tri-n-butyltin hydride in the presence of azobisisobutyronitrile (AIBN) in benzene at 70 °C for 7–13 h to afford 3-p-tolylsulphonyl-4-alkyltetrahydrofurans (5) in which the trans-isomer predominated. The substituents on the olefinic carbon have a market effect on the stereochemical course of the cyclization. 1-Bromo-1-p-tolylsulphonyl-2-allylaminoethane (4) gave the pyrrolidine derivative (6) more stereoselectively. These results are discussed in terms of the steric factors. Similarly, 1-bromo-1-p-tolylsulphonyl-2-prop-2-ynyloxyethane derivatives (3) produced 3-p-tolylsulphonyl-4-alkylidenetetrahydrofurans (9).

Directed 2-azonia-[3,3]-sigmatropic rearrangements. a convenient preparation of substituted 1-azaspiro[4,5]decanes

Abstract 3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement.

Functionalization and hybridization of poly(vinyl chloride) III. Transformation of poly(vinyl chloride) into water-crosslinkable polymer☆

Abstract A trimethoxysilyl group, which reacts easily with water, was introduced into poly(vinyl chloride) (PVC) in homogeneous and heterogeneous reactions. The polymers obtained were crosslinked in the presence of water, and crosslinking was accelerated in the presence of acid or base.

Synthesis and complex formation of diferrocenyltetrathiafulvalene

Diferrocenyltetrathiafulvalene (2) contains two electron donor sites, the tetrathiafulvalene and ferrocene units; its charge transfer complexes with acceptor molecules such as tetracyanoquinodimethane (TCNQ) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) have been isolated.