Teiichi Murakami

Regioselective sulfonation of a secondary hydroxyl group of cyclodextrins

Abstract A new and convenient procedure has been developed for the regioselective tosylation of a C-2 hydroxyl group of cyclodextrins via cyclic tin intermediate.

Regio- and stereocontrolled synthesis of d-erythro-sphingosine and phytosphingosine from d-glucosamine

d-erythro-Sphingosine (1) and phytosphingosine (2) have been efficiently synthesized from d-glucosamine by utilizing its whole carbon skeleton and functional groups. In this synthetic route, regioselective alkylation of the epoxy-tosylate 9 was achieved with a copper(I)-catalyzed Grignard reagent to give the key intermediate 10, which was converted to both 1 and 2 via regioselective formation of the iodohydrin 11.

Synthesis of 1,3-di-O-alkyl-2-O-(β-glycosyl)glycerols bearing oligosaccharides as hydrophilic groups

A novel series of synthetic glycolipids, 1,3-di-O-alkyl-2-O-(beta-glycosyl)glycerols, and their efficient synthetic route were proposed. These glyceroglycolipids were synthesized in good overall yields and stereoselectivity in five steps via trichloroacetimidate glycosylation with 1,3-di-O-alkylglycerols. This route was applied to prepare the glycolipids bearing a cello- or malto-oligosaccharide with a definite number of sugar residues from one to six. Thin-layer chromatography, elemental analysis, nuclear magnetic resonance spectroscopy and infrared absorption spectroscopy confirmed that these glycolipids were chemically pure compounds.

Occurrence, Structure and Taxonomic Implications of Fern Constituents

The living ferns constitute a large group in the plant kingdom, including as they do about 12,000 species (Pichi Sermolli 1960) (1). They are usually divided into three orders, Ophioglossales, Marattiales and Filicales. The Ophioglossales are sometimes regarded as a distinct class. Both the Ophioglossales and the Marattiales have sporangia which have developed from a group of initial cells (eusporangiate ferns), with the Marattiales being usually regarded as being more primitive than the Filicales whose sporangia originate from a single cell (leptosporangiate ferns). The Osmundaceae are considered to be a primitive member of the Filicales by some authorities and to belong to a separate order by others (2). Indeed, many different systems for classifying the ferns have been proposed, for example, by Christensen 1938 (3); Ching 1940 (4); Copeland) 1947 (5); Holttum 1947 (6); Reimers) 1954 (7); Alston) 1956 (8) and Picni Sermolli) 1958 (9) Even today, pteridologists appear to be of different opinions as regard the grouping of fern taxa, particularly the polypodiaceous ferns, and their phylogenetic relationships. Even the number of the families to be included in the Filicopsida which are recognized by different pteridologists varies from twelve to more than fifty (10). Table 1 shows the relations between the three representative systems of classification of the polypodiaceous ferns (sensu lato) proposed by Copeland (1947), Picm Sermolli (1970) (9b, 11) and Holttum (1947). The tentative classification system which is refered to throughout this review is also shown in Table 1.

An efficient synthesis of 5-diethoxymethylimidazole-4-carboxylate, a potential precursor for various imidazole derivatives

Abstract Anionic cycloaddition of methyl isocyanoacetate to diethoxyacetonitrile afforded methyl 5-diethoxymethylimidazole-4-carboxylate, a useful imidazole nucleus with two different functional groups.

Improved Synthesis of (4S)-4-[(1S,2R)-1,2-Epoxybut-3-enyl]-2-phenyl-2-oxazoline, a Key Intermediate for Sphingolipids1

Abstract Abstract: The title compound has been conveniently synthesized from N-benzoyl-D-glucosamine by a novel route using oxidative bromination of benzylidene acetal as a key step.

Efficient stereocontrolled synthesis of D-erythro-sphingosine from N-benzoyl-D-glucosamine

D-erythro-Sphingosine is synthesized from N-benzoyl-D-glucosamine 2 in a highly regio- and stereocontrolled manner. The key features in the synthesis involve the efficient conversion of compound 2 into the vinyl epoxide 10 and the subsequent SN2′-type reaction with a Grignard reagent in the presence of CuCN to afford the 1-O,2-N-protected sphingosine 11.