Toshifumi Kageyama

Synthesis of isoxazolines and isoxazoles from aldoximes by the use of sodium bromite with organotin halide

Abstract The oxidizing system using sodium bromite with a catalytic amount of tri-butyltin chloride is applied for the preparations of isoxazolines and isoxazoles from aldoximes via dipolar cycloaddition.

Tributylstannylated silicic acid as precursor of organofunctionalized silica gel

Tributylstannylated silicic acid (TBSA), which was regarded as a protected polymeric silanol against self-condensation to give silica gel, was newly prepared from the reaction of water glass (WG) and bis(tributyltin) oxide (TBO). The ratios of Si/Sn contained in TBSA were determined by gravimetric analysis to be in the range of 2–3. The gelation of TBSA in usual organic solvents such as hexane, benzene, and dichloromethane was not observed over 3 weeks. In addition, TBSA was shown to be a convenient precursor for the preparations of silica gel modified with organofunctional groups. From the reaction of TBSA with trimethoxysilanes and aromatic alcohols, the silica gels havingorganofunctional groups were obtained with the elimination of a tributyltin group.

Synthesis of organofunctionalized polysiloxane from polymeric tributylstannyl ester of silicic acid and chlorosilanes

Polymeric tributylstannyl ester of silicic acid (PTBS) was demonstrated to be an effective material for the preparation of functionalized polysiloxane derivatives (2). The reaction of PTBS and monochlorosilane (1), which possessed an organofunctional group such as the acetoxy or methylmethacrylate group, proceeded readily at room temperature under neutral conditions to give 2 with the elimination of the tributyltin group. The molecular weight of 2 estimated by GPC measurement was almost the same as that of starting PTBS. Such metal-exchange reaction was applicable for the incorporation of two kinds of silyl units into polysiloxane 2 by employing these monochlorosilanes 1 at the same time in the reaction.

Synthetic application of tributylstannyl ester of silicic acid: Synthesis and polymerization of polysiloxane having methacryloyloxypropyl groups

Polymeric tributylstannyl ester of silicic acid (PTBS) was demonstrated to be a useful intermediary compound for the preparation of polysiloxane derivative (MPS), which possessed methacryloyloxypropyl groups. The reaction of PTBS and (3-methacryloyloxypropyl)dimethylchlorosilane (1a) proceeded readily at room temperature under neutral conditions to give MPS with the elimination of tributyltin group. The reaction conducted in the presence of 1a and trimethylchlorosilane (1b) was effective for the preparation of MPS containing the both silyl groups, in which the content of methacryloyloxy groups could be controlled. The obtained MPS polymerized readily under UV irradiation to afford the organic–inorganic hybrid resin (MSR) as a kind of organically modified silica gel.

Synthesis of Organofunctionalized Silica Gel from Organostannio Silica Gel and Alkoxysilane.

Organofunctionalized silica gel was readily prepared from the organostannio silica gel, which had dib utyl or tributylstannio group, and (3-methacryloxypropyl) trimethoxysilane. The reaction in the presence of acid or base catalyst proceeded with the elimination of organotin group to produce the silica gel having a high content of the organofunctional group.

A new synthetic route to alkenyl-substituted tetrahydrofurans via successive intra- and inter-molecular radical reactions

Tetrahydrofurans with alkenyl substituents were obtained by the radical cyclization of β-bromoethers using allyltri-n-butylstannane in a one-pot reaction.