Shigenobu Arihara
Tohoku University
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Tetrahedron | 1976
Hiroshi Hikino; K. Mohri; Yasuko Hikino; Shigenobu Arihara; Tsunematsu Takemoto; H. Mori; K. Shibata
Abstract Inokosterone, a phytoecdysone isolated from Achyranthes fauriei (Amaranthaceae), has been partially acetylated to give the 2,26-diacetate (4) which has been converted into methyl 5 - acetoxy - 4 - methylpentanoate (7), showing no apparent [α]D, and 2β - acetoxy - 3β,14α - dihydroxy - 5β - pregn - 7 - ene - 6,20 - dione (8). Chemical and physiochemical studies have shown the configurations at C-20 and C-22 to be R. Inokosterone has thus been concluded to be a mixture of C-25 epimers of (20R,22R) - 2β,3β,14α,20,22,26 - hexahydroxy - 5β - cholest - 7 - en - 6 - one (1). After the synthesis of the model compound, a C-25 epimeric mixture of (20R,22R) - 3β,20,22,26 - tetrahydroxy - 5α - cholestane (23), inokosterone has been synthesized via (20R) - 2β,3β,14α,20 - tetrahydroxy - 20 - formyl - 5β - pregn - 7 - en - 6 - one (25) by Grignard reaction with 4 - (tetrahydrofuran - 2 - yloxy) - 3 - methylbutynylmagnesium bromide (15) followed by hydrogenation and hydrolysis. The use of an NMR shift reagent with the inokosterone acetates (9, 29) and the optical activity measurement of α - methylglutaric acid (3) derived from inokosterone have established that inokosterone is a 1:2 mixture of the C-25 R and S epimers.
Tetrahedron | 1969
Hiroshi Hikino; Shigenobu Arihara; Tsunematsu Takemoto
Abstract A novel glycoside of an insect-metamorphosing substance, ponasteroside A, has been isolated from Pteridium aquilinum var. latiusculum (Pteridaceae). Chemical and physico-chemical properties of ponasteroside A and its hexaacetate (IV) and, in particular, its enzymatic hydrolysis into ponasterone A (II) and glucose have established the structure and absolute configuration of ponasteroside A as represented by formula 1.
Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan | 1983
Tsunematsu Takemoto; Shigenobu Arihara; Tadashi Nakajima; Megumi Okuhira
Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan | 1983
Tsunematsu Takemoto; Shigenobu Arihara; Tadashi Nakajima; Megumi Okuhira
Chemical & Pharmaceutical Bulletin | 1975
Hiroshi Hikino; Toru Okuyama; Shigenobu Arihara; Yasuko Hikino; Tsunematsu Takemoto; Hiromu Mori; Kenyu Shibata
Chemical & Pharmaceutical Bulletin | 1970
Hiroshi Hikino; Taeko Takahashi; Shigenobu Arihara; Tsunematsu Takemoto
Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan | 1983
Tsunematsu Takemoto; Shigenobu Arihara; Tadashi Nakajima; Megumi Okuhira
Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan | 1983
Tsunematsu Takemoto; Shigenobu Arihara; Tadashi Nakajima; Megumi Okuhira
Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan | 1967
Tsunematsu Takemoto; Shuntaro Ogawa; Nobushige Nishimoto; Shigenobu Arihara; Kazuo Bue
Tetrahedron Letters | 1968
Tsunematsu Takemoto; Shigenobu Arihara; Hiroshi Hikino