Shinsuke Nakahara

Synthetic studies on pentacyclic aromatic alkaloids, kuanoniamine A, 11-hydroxyascididemin, and neocalliactine acetate

Abstract A pentacyclic aromatic alkaloid, kuanoniamine A (6) was synthesized in three steps from 6-methoxybenzothiazole-4,7-dione (8) and 2-aminoacetophenone (9). 11-Hydroxyascididemin (4) was prepared from 5,8-quinolinedione (13, 14) or 1,4-acridinedione (20). The structure of neocalliactine acetate, a derivative of calliactine, was determined to be 5 by total synthesis from 6-methoxy-5,8-quinolinedione (28) and 2-amino-5-methoxyacetophenone (29).

Mimocin, a new isoquinolinequinone antibiotic

Abstract A new isoquinolinequinone antibiotic, mimocin(2), has been isolated from the strain of Streptomyces lavendulae . The structure of mimocin has been deduced from mass and PMR spectral data and confirmed by its synthesis.

Total synthesis of kuanoniamine A, 11-hydroxy-ascididemin, and neocalliactine acetate

A pentacyclic aromatic alkaloid, kuanoniamine A (5) was synthesized from 6-methoxybenzothiazole-4,7-dione (7) and 2-aminoacetophenone (8). Similarly, 11-hydroxyascididemin (4) was prepared from 6-bromo-4-chloro-5,8-dimethoxyquinoline (12). The structure of neocalliactine acetate, a derivative of calliactine, was determined as 19 by total synthesis from 6-methoxy-5,8-quinolinedione (23) and 2-amino-5-methoxyacetophenone (24)

Total synthesis of eilatin

Synthesis of the symmetrical pentacyclic fused aromatic alkaloid called eilatin (1) is described

Synthesis of 2(1H)-quinolinonequinones and 2-alkoxy-quinolinequinones using oxidative demethylation with cerium (IV) ammonium nitrate

2,5,8(1H)-Quinolinetriones (12), 2,5,6(1H)-quinolinetriones (13), 2-alkoxy-5,8-quinolinediones (14), 2,8-dimethoxy-5,6-quinolinedione (15), and 2,6-dimethoxy-7,8-quinolinediones (16) were synthesized by oxidative demethylation of the corresponding 2(1H-quinolinones (7) and 2-alkoxyquinolines (11) with cerium (IV) ammonium nitrate

The structures of novel antibiotics, saframycin B and C

Abstract The structure of saframycin C(3) has been established by an X-ray crystallographic analysis; this result allows the assignment of structure to the closely related saframycin B(2) by 13 C NMR spectroscopy.

Synthesis of 5,8-quinoxalinediones and 5,8-quinazolinediones

5,8-Quinoxalinediones (3a-c, 12, 13), dibenzo[a,c]phenazine-10, 13-diones (5a, b), 5,8-quinazolinediones (17, 23), and 4,5,8(3H)-quinazolinetrione (21) were prepared using oxidative demethylation of the corresponding 5,8-dimethoxy compounds with cerium (IV) ammonium nitrate

Synthesis of pantherinine, a cytotoxic fused tetracyclic aromatic alkaloid

Abstract A cytotoxic fused tetracyclic aromatic alkaloid, pantherinine ( 1 ) from the ascidian aplidium pantherinum , was synthesized using biaryl cross-coupling reaction.