Shigeki Habaue

Regioselective allylation and propargylation using acylsilanes: facile synthesis of PGE3 and F3α methyl ester

Abstract Regioselective allylation and propargylation were achieved using acylsilanes as electrophiles and this methodology was applied to the synthesis of PGE3 and F3α methyl ester.

Stereospecific polymerization of benzyl α-(alkoxymethyl) acrylates

a-(Alkoxymethyl)acrylates, such as methyl α-(phenoxymethyl)acrylate, benzyl α-(methoxymethyl) acrylate (BMMA), benzyl α-(benzyloxymethyl) acrylate, and benzylα-(tert-butoxymethyl)acrylate, were synthesized, and their polymerizability and the stereoregularity of the polymers obtained by radical and anionic methods were investigated. The radically obtained polymers were found to be atactic by 13 C- and 1 H-NMR analyses, but the polymers obtained with lithium reagents in toluene at -78°C were highly isotactic. Further, it is noteworthy that isotactic polymers were also produced with lithium reagents even in tetrahydrofuran. Effects of polymerization temperature and counter cation on stereoregularity were clearly observed in the polymerization of BMMA, and a potassium reagent afforded an almost atactic polymer.

Anionic polymerization of o‐substituted styrene derivatives: Control of reactivity and stereochemistry by aminomethyl group

Ortho-substituted styrenes, such as 2-(N,N-dimethylaminomethyl)styrene (1), 2-(1-pyrrolidinylmethyl)styrene (2), and 2-[(S)-2-(1-pyrrolidinylmethyl)-1-pyrrolidinylmethyl]styrene (3), were synthesized, and the effects of the ortho-substituents on the polymerizability and stereoregularity of the obtained polymers using the anionic method were examined. The bulkiness and coordination of the ortho-substituted amino groups to the counter cation significantly affected the polymerizability and stereochemistry of the obtained polymers. The anionic and radical polymerizations of 2 with a less hindered ortho-substituent afforded polymers in good yields, whereas those of 1 and 3 resulted in lower yields. The anionic polymerization of 3 bearing an optically active diamine derivative at the ortho-position with n-butyllithium in toluene at 0 °C gave a polymer with a high stereoregularity and stable regular conformation based on the stereoregular backbone structure.

Chemospecific ring-opening polymerization of α-methylenemacrolides

α-Methylenemacrolides having various groups, such as aromatic, ether, and amine, were enzymatically, anionically, and radically polymerized. The polymerization with the lipase catalyst successfully afforded polymers only through the ring-opening process, whereas the vinyl polymerizations selectively proceeded by using anionic and radical initiators. The polyesters obtained by the enzymatic polymerization have a polymerizable methacrylic methylene group in the main-chain, in addition to the aromatic and polar groups, and were further radically polymerized to quantitatively produce a cross-linked polymer gel.

Synthesis and Chiral Recognition of Helical Polymers

Abstract Asymmetric syntheses of optically active polymethacrylate, polyacrylate, polyacrylamide, and polyisocyanate with helical conformation and their chiral recognition abilities are described. 1-Phenyldibenzosuberyl methacrylate (PDBSMA) gave a purely onehanded-helical, optically active polymer ([α]365 +1670 ∼ +1780o) with almost perfectly isotactic structure by anionic polymerization using optically active initiators. Radical polymerizations of PDBSMA using chiral initiators, chain transfer agents, and additives also afforded optically active polymers with a prevailing onehanded helicity. Triphenylmethyl acrylate yielded an optically active, helical polymer ([α]365 +102o) having a dyad isotacticity of 70% using an optically active anionic initiator. Although the polyacrylate demonstrated chiral recognition ability as a chiral stationary phase for HPLC, the ability was low mainly because of the low degree of one-handedness. N-(3-Chlorophenyl)-N-phenylacrylamide gave an optically active, helical polyme...

Stereospecific anionic polymerization of α-(alkoxymethyl)acrylate derivatives affording novel vinyl polymers with macrocyclic side chains

Abstract Macrocyclic α-(alkoxymethyl)acrylates such as 2-methylene-4-oxa-12-dodecanolide, 2-methylene-4-oxa-16-hexadecanolide, 8,9-benzo-2-methylene-4,7,10-trioxa-8-dodecen-12-olide and 9,10-benzo-2-methylene-4,8,11-trioxa-9-tetradecen-14-olide were synthesized and their polymerizability and the stereoregularity of the obtained polymers by radical and anionic methods were investigated. The anionically obtained polymers possessed a normal vinyl polymer structure, and the polymerization with organolithium and Grignard reagents afforded isotactic-rich polymers, whereas the polymers obtained with potassium biphenylide were almost atactic based on their 1H NMR analysis. The anionically obtained polymers bearing a crown ether-type side chain demonstrated a cobalt ion transport ability as a synthetic ion channel using vesicles prepared with dihexadecyl phosphate.

Polymerization and asymmetric oligomerization of allylsilanes using chiral ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium and -hafnium complexes

Stereospecific polymerization and-asymmetric oligomerization of allylsilanes were investigated by using C 2 - and C,-symmetric zirconocene catalysts. Isotactic and syndiotactic poly(allylsilane)s were produced with rac-ethylenebis(4,5,6,7-tetrahydro 1-indenyl)zirconium dichloride (1) and diphenylmethylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl))zirconium dichloride (6), respectively. Bulky allylsilanes afforded optically active oligomers in the reactions using optically active ethylenebis(4,5,6,7-tetrahydro- 1-indenyl)zirconium and -hafnium complexes.

Nickel-catalyzed regioselective allylation of allylic alcohols

Abstract Regioselective allylmetallation of allylic alcohol has been accomplished by treatment with allylzinc in the presence of a nickel catalyst. Benzylic protective group of allyl alcohol facilitates the allylmetallation.

Helical Polymers: Synthesis, Conformation, and Function

Asymmetric polymerization of acrylic monomers and an isocyanate derivative leading to a helical conformation is described. 1-Phenyldibenzosuberyl methacrylate, triphenylmethyl acrylate, and N,N-diphenylacrylamide were polymerized using the complexes of diphenylethylenediamine monolithium amide with (-)-sparteine, (S,S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)butane, and (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine. The methacrylate gave a purely one-handed helical, optically active polymer ([α]365 +1670° ~ +1780°) having a perfect isotactic structure; the polymer exhibited chiral recognition ability to some racemic compounds. This monomer gave optically active polymers also by radical mechanism. The acrylate also gave an optically active, helical polymer ([α]365 +102°) having a dyad isotacticity of 70% using the pyrrolidine complex. The poly(methyl acrylate) derived from the polyacrylate showed a specific rotation which appears to be based on configurational chirality of the main chain. The acrylamide gave an optically active polymer ([α]365-429°) which may have a helical structure by asymmetric anionic polymerization; the polymer had a dyad isotacticity of 86%. m-Methylphenyl isocyanate was polymerized using optically active lithium alkoxides and amides to produce a polymer having a chiral group at the α-end. A prevailing one-handed helical structure was induced for the main chain due to the chiral end group.