Synthesis of 1-(1H-Imidazol-2-yl)ethane-1,2-diol Derivatives: A novel class of protein kinase C inhibitors

First synthesis of double headed 1,3,4-oxadiazino[6,5-b]indole acyclo C-nucleosides

Condensation of 1,3-dihydro-2,3-dioxo-2H-indoles (la-c) with galactaric acid bis hydrazide (2) gave the corresponding galactaric acid bis[2-(1,2-dihydro-2-oxo-3H-indol-3-ylidene)hydrazides] (3a-c). Acetylation of the latter compounds with acetic anhydride in the presence of pyridine at ambient temperature gave the 2,3,4,5-tetra-O-acetylgalactaric acid bis[2-(1,2-dihydro-2-oxo-1-substituted-3H-indol-3-ylidene)hydrazides] (4b-d). Heterocyclization of the tetra-O-acetates 4b-d by heating with thionyl chloride afforded the double headed acyclo C-nucleosides: 1,2,3,4-tetra-O-acetyl- 1,4-bis[9-substituted-1,3,4-oxadiazino[6,5-b]indol-2-yl-1-ium]-galacto-tetritol dichlorides (5b-d). Structures of the prepared compounds were elucidated from their spectral properties.

Synthesis of double headed imidazoline acyclo C-nucleosides: 1,4-bis[1-amino-5-oxo-4-substituted(imidazolin-2-yl)]galacto-tetritols

Condensation of 2,3,4,5-tetra-O-acetyl-galactaroyl dichloride (1) with two equivalents of the alpha-amino esters 2a-c gave the corresponding 2,3,4,5-tetra-O-acetyl-galactaric acid diamides 3a-c. Heterocyclization of 3a-c by heating with hydrazine hydrate took place with concomitant de-O-acetylation of the polyacetoxyalkyl chain to give 1,4-bis[1-amino-5-oxo-4-substituted(imidazolin-2-yl)] galacto-tetritols (5a-c) and not the theoretically possible 1,2,4-triazinones 4 as indicated by spectral data. Compounds 5a-c readily reacted with p-nitrobenzaldehyde to give the corresponding p-nitrobenzylideneamino derivatives 6a-c. Acetylation of 5a-c afforded the 2,3,4,5-tetra-O-acetyl-1,4-bis[1-acetamido-5-oxo-4-substituted(imidazolin-2-yl)]galacto-tetritols (7a,b,d). De-O-acetylation of 7a,b,d gave 1,4-bis[1-acetamido-5-oxo-4-substituted (imidazolin-2-yl)]galacto-tetritols (8a-c).