Akinori Kubo

SYNTHESIS OF SAFRAMYCINS. XI, SYNTHETIC STUDIES TOWARD A TOTAL SYNTHESIS OF SAFRACIN A

Abstract A synthetic strategy for the preparation of the isoquinolinequinone antibiotic safracin A ( 1a ) is outlined. Our initial strategy for the construction of the ABC ring was based on a retrosynthetic analysis. Conversion of 5 in five steps to the imide 16 vas followed by a 1,2-reduclion with lithium tri-tert-butoxyaluminum hydride to give the allylic alcohol 7a . This compound was then cyclized to the 1,5-imino-3-benzazocine 8a and the indeno[1,2-b]pyrazin-2-one 17 . An unwanted isomer 17 was converted to the N-methyl tetracyclic lactam 21 , the structure of which was determined by X-ray crystallography. Conversion of 18 to the pentacyclic pyruvamide 31 was completed in a nine step sequence. Finally, 31 was subjected to a two-step oxidative demethylation to provide the quinones 10a and 34 . An unsuccessful attempt to introduce a hydroxyl group onto the C-I position of the quinones 10a or 34 is also described.

Synthetic studies of imbiline 1, a constituent of Eupomatia species

Abstract Imbiline 1 ( 1a ), a constituent of Eupomatia species, was synthesized from 4-methoxy-1-naphthylamine hydrochloride ( 8 ) in seven steps. A reaction of aldehydes and methyl methylthiomethyl sulfoxide was also studied.

Structure of Saframycin R

Abstract The structure of saframycin R was determined to be 1 (form I) by the two-dimensional 1H detected heteronuclear correlation experiments (HMQC and HMBC) of its acylated compounds 4a and 4b.

Synthesis of imbiline 1, a tetracyclic aza-aromatic alkaloid

A tetracyclic aza-aromatic alkaloid, imbiline 1 (1) was synthesised from 1-amino-4-methoxynaphthalene hydrochloride (7) in seven steps.