An improved, convenient procedure for reduction of amino acids to aminoalcohols: Use of NaBH4-H2SO4

Abiko, Atsushi; Masamune, Satoru

doi:10.1016/s0040-4039(00)61133-4

Cited by 190 publications

(106 citation statements)

References 7 publications

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“…Chiral non-racemic silyloxypyrrole 3 was readily prepared (Scheme 2) from (R)-(-)-2-phenylglycinol, which in turn was readily obtained by reduction of (R)-(-)-2-phenylglycine with lithium borohydride and chlorotrimethylsilane 8,9 (R)-(-)-2-Phenylglycinol was then reacted with 2,5-dimethoxy-2,5-dihydrofuran in water at pH 1 to afford dihydropyrrol-2-one 1. The optimal reaction time was 3 h; if longer times were used, the yield of the desired product decreased.…”

Section: Resultsmentioning

confidence: 99%

Addition of a chiral non-racemic silyloxypyrrole to an activated 1,4-benzoquinone

Halim¹,

Brimble²,

Woodgate³

2002

Arkivoc

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The uncatalyzed addition of enantiopure silyloxypyrrole 3 to 2-carbomethoxy-1,4-benzoquinone 4 in acetonitrile at ambient temperature afforded pyrrolidinonobenzofuran adducts 5 and 6 in low yield. The two adducts were separated by flash chromatography and the structures of these diastereomers were determined using high field NMR spectroscopy combined with molecular modelling studies. The work reported herein provides the first example of the annulation of a 1,4-benzoquinone with a chiral non-racemic silyloxypyrrole.

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Section: Resultsmentioning

confidence: 99%

Addition of a chiral non-racemic silyloxypyrrole to an activated 1,4-benzoquinone

Halim¹,

Brimble²,

Woodgate³

2002

Arkivoc

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“…Celite 545 was purchased from SigmaAldrich (Tokyo, Japan). 3,5-Diiodobenzoic acid (5), 23 (S)-phenylalaninol (7a) and (S)-phenylglycinol (7b) 24 were synthesized in accordance with a method published in the literature. n-Hexane, ethyl acetate, tetrahydrofuran, toluene, N,N¢-dimethylformamide, dimethylsulfoxide, 1,2-dichloroethane, CH 2 Cl 2 and CHCl 3 were dried according to the standard procedure and distilled under nitrogen atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and characterization of optically active poly(phenylene-ethynylene)s containing chiral oxazoline derivatives

Rattanatraicharoen

Yamabuki

Oishi

et al. 2011

Polym J

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Novel optically active (S)-2-(3,5-diiodophenyl)oxazoline derivatives ((S)-DIPhROx)) (R¼4-benzyl (1a), 4-phenyl (1b)) were synthesized and polymerized using the Sonogashira-Hagihara coupling reaction to obtain the poly(phenylene-ethynylene)s bearing oxazoline derivatives in the weight range from 1060 to 17 300 in 40-72% yields. The polymers were thermally stable up to 220 1C. All the polymers exhibited higher specific rotation values than the model compound did. Moreover, these polymers also showed intense circular dichroism (CD) signals in the transition region of the conjugated main chain, whereas almost no induced Cotton effect was observed for the model compound. The results of the specific rotation and CD and ultraviolet analyses indicate that the optical activities of the polymers arise not only from the configurational chirality of the optically active oxazoline pendant groups but also from elements of higher-order structure such as the helical conformation.

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“…Bnbox was prepared from diethylmalonyl dichloride and (S )-phenylalaninol according to the reported methods 11,12 ([α] …”

Section: Chiral Ligandsmentioning

confidence: 99%

Asymmetric Polymerization of N-ortho- or para-Substituted Phenylmaleimide Using Chiral Anionic Initiators

Oishi

Isobe

Onimura

et al. 2003

Polym J

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ABSTRACT:N-Phenylmaleimide (PhMI) and its derivatives were polymerized using chiral anionic initiators consisting of diethylzinc (Et 2 Zn) and chiral ligands to investigate the effect of the bulkiness, flexibility and polarity of the ortho-or para-substituents on optical activity of the obtained polymer. The optical activity of the polymer was extremely influenced by N-substituents, initiators, and other polymerization conditions. Poly(N-2-biphenylmaleimide) (poly(2-BPMI)) formed with Et 2 Zn-(-)-2,2 -(1-ethylpropylidene)bis(4-benzyl-2-oxazoline) (Bnbox) showed the highest specific rotation ([α] 25 435 ) of +164.7• . From 13 C NMR spectroscopy, optically active poly(2-BPMI) and poly(N-(2-phenoxy)-phenylmaleimide) (poly(2-POPMI)) mainly possessed threo-diisotactic structures in the main chains. Chiral stationary phase prepared from optically active poly(PhMI) optically resolved racemic 1,1 -bi-2-naphthol.KEY WORDS N-Substituted Maleimide / Asymmetric Anionic Polymerization / Chiral Ligand / Optically Active Polymer / N-Substituted maleimide (RMI) is one of the interesting monomers which can form an optically active polymer. [1][2][3][4][5] Main chain carbons of poly(RMI) are chiral because polymerization of RMI proceeds through only trans-opening reaction of double bond in the imide ring. 6 Structures of poly(RMI) produced by trans-addition reactions are displayed in Chart 1. In threo-disyndiotactic structures, stereogenic centers (S , S ) and (R, R) in each monomeric unit equally exist, so that main chain carbons of poly(RMI) do not exhibit optical activity. Threo-diisotactic structures exert optical activity only if either of configurational pairs of (S , S ) or (R, R) predominantly is formed in the trans-main chains. Furthermore, when the same configurational pairs are successively connected in the threo-diisotactic sequences, the polymer main chains can form a helical conformation. If poly(RMI) contains the sequences of helical conformation, the polymer has not only configurational chirality but also conformational one.Systematic research on asymmetric anionic polymerization of achiral RMI bearing aromatic groups has been performed by the authors. 4, 5 Optical activity of poly(RMI) was significantly affected by a structure of N-substituent. The authors investigated the effect of bulkiness of N-substituent on optical activity of poly(RMI) prepared by asymmetric anionic polymerization. = −36.8 • to +762.3 • ) formed by asymmetric anionic method was the highest in all of poly(RMI)s obtained so far. Thus, bulky N-substituents did not always provide high optical activity to the obtained poly(RMI). Therefore, further studies on the effect of N-substituents of RMI on optical activity of the polymer are currently desirable.In this paper, we introduced a substituent into the ortho-or para-position of phenyl group of PhMI, and Chart 1.

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An improved, convenient procedure for reduction of amino acids to aminoalcohols: Use of NaBH4-H2SO4

Cited by 190 publications

References 7 publications

Addition of a chiral non-racemic silyloxypyrrole to an activated 1,4-benzoquinone

Addition of a chiral non-racemic silyloxypyrrole to an activated 1,4-benzoquinone

Synthesis and characterization of optically active poly(phenylene-ethynylene)s containing chiral oxazoline derivatives

Asymmetric Polymerization of N-ortho- or para-Substituted Phenylmaleimide Using Chiral Anionic Initiators

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