Nobuya Katagiri

A Novel Entry to Pyrido[4,3-b]carbazoles: An Efficient Synthesis of Ellipticine

Abstract The palladium catalyzed tandem cyclization–cross-coupling reaction of indolylborate (2) with vinyl bromide (9) was developed for the preparation of pyrido[4,3-b]carbazole as a key reaction. The cross-coupling reaction of 2a provided hexatriene (10), and then cyclization of 10 to pyrido[4,3-b]carbazole (12) was effected with irradiation or Lewis acid. Using indolylborate (2c) for the cross-coupling reaction, a novel construction of ellipticine was attained through similar reaction sequences.

The first synthesis of a 2′,3′-methano carbocyclic nucleoside

Abstract A 2′,3′-methano carbocyclic nucleoside, 9-( c -4-hydroxymethylbicyclo[3.1.0]hex- r -2-yl)-9 H -adenine, has been efficiently synthesized from 2-azabicyclo[2.2.1]hex-5-en-3-one(ABH) in six steps involving 1,3-dipolar cycloaddition, photolysis, and adenine ring construction.

A concise access to 2-allenylindole derivatives based on the palladium catalyzed cross-coupling reaction of indolylborates

Abstract The palladium catalyzed cross-coupling reaction of trialkyl(indol-2-yl)borates with prop-2-ynyl carbonates was developed for the preparation of 2-allenylindole derivatives. When the reaction of indolylborates with tert -prop-2-ynyl carbonates was carried out, 2-allenylindoles were obtained solely. Otherwise, indolylborates reacted with sec -prop-2-ynyl carbonates, giving rise to 2-allenylindoles and/or 3-(prop-2-ynyl)-indoles depending on the catalyst used.

First synthesis of 2′,3′-epimino-carbocyclic nucleosides

The preparation of 2,3-epimino-carbocyclic analogues of adenosine is reported. The reaction of p-tosyl azide with N-substituted 2-azabicyclo[2.2.1]hept-5-en-3-one (ABH) (1a) provided aziridine-fused ABH (2), which was converted to 2,3-epimino-carbocyclic nucleosides (11).

Synthesis and Hybridization Property of Oligonucleotides Containing Carbocyclic Oxetanocins

Abstract Oligonucleotides containing enantiomeric carbocyclic oxetanocins possessing adenine, thymine, guanine and cytosine were synthesized from an optically active cyclobutane derivative. Their hybridization properties with the complementary oligonucleotides were studied using melting point method, CD spectroscopy, and mixing curve method (Job plots). The artificial nucleotides possessing adenine, guanine and cytosine bases show tendency to form complexes more strongly with ribonucleotide than deoxyribonucelotide. These complexes are triplexes consisting of purine and pyrimidine in 1:2 ratio. Such triplex formation is observed both under high (1xa0M NaCl) and low salt conditions (0.1xa0M NaCl).