Neste trabalho estão descritas as sínteses dos ribonucleosídeos pirrólicos reversos 5-C-(4-acetil-5-metil-pirrol-1-il)-2,3-O-isopropilideno-5-desoxi- beta-D-ribofuranosídeo de metila (10), 5-C-(4-etoxicarbonil-5-metil-pirrol-1-il)-2,3-O-isopropilideno-5-desoxi- beta-D-ribofuranosídeo de metila (11), 5-C-(4-acetil-5-metil-pirrol-1-il)-5-desoxi-beta-D-ribofuranosídeo de metila (12), 5-C-(4-etoxicarbonil-5-metil-pirrol-1-il)-5-desoxi- beta-D-ribofuranosídeo de metila (13), 5-desoxi-5-C-(3'-formil-4'-hidroxipropil-pirrol-1'-il)-2,3-O-isopropilideno- beta-D-ribofuranosídeo de metila (16) e 5-desoxi-5-C-(3'-formil-pirrol-1'-il)-2,3-O-isopropilideno- beta-D-ribofuranosídeo de metila (18) a partir do 5-amino-5-desoxi-2,3-O-isopropilideno-beta-D-ribofuranosídeo de metila (9), matéria-prima de fácil preparação. A estratégia sintética para a construção do anel heterocíclico baseou-se no ataque nucleofílico da amina 9 aos diidrofuranos: 4-acetil-2-n-butoxi-5-metil-4,5-diidrofurano (4), 4-carbetoxi-2-n-butoxi-5-metil-4,5-diidrofurano (5), 4-formil-2-n-butoxi-4,5-diidrofurano (6) e 4-formil-1-metil dioxabiciclo[3.3.0]oct-3-eno (8, in situ), obtidos através da reação dos diazo compostos 3-diazo-2,4-pentadiona (1), 2-diazoacetoacetato de etila (2) e diazomalonaldeído (3) com enol-éteres, sob catálise de tetraacetato de di-ródio.

The synthesis of reverse pyrrole ribonucleosides methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl)-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (10), methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl)-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (11), methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl)-5-deoxy-beta-D-ribofuranoside (12), methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl)-5-deoxy- beta-D-ribofuranoside (13), methyl 5-deoxy-5-C-(3'-formyl-4'-hydroxypropyl-pyrrol-1'-yl)-2,3-O-isopropylidene- beta-D-ribofuranoside (16) and methyl 5-deoxy-5-C-(3'-formyl-pyrrol-1'-yl)-2,3-O-isopropylidene- beta-D-ribofuranoside (18) are described starting from readily available methyl 5-amino-5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranoside (9). The synthetic strategy for the construction of the heterocyclic ring was based on the nucleophilic attack of (9) to 4-acetyl-2-n-butoxy-5-methyl-4,5-dihydrofuran (4), 4-carbetoxy-2-n-butoxy-5-methyl-4,5-dihydrofuran (5), 4-formyl-2-n-butoxy-4,5-dihydrofuran (6) and 4-formyl-1-methyl dioxabyciclo[3.3.0]oct-3-en (8, in situ). The later compounds were obtained from reaction between 3-diazo-2,4-pentadione (1), ethyl 2-diazoacetoacetate (2) or diazomalonaldehyde (3) and enol ethers using dirhodium tetraacetate as a catalyst.

Diazocarbonyl compounds are a very important class of organic substances which have a long history of useful aplications in organic chemistry. The focus of this report deals with the use of diazocarbonyl compounds in a ariety of important reactions and their application in organic synthesis. These reactions are briefly summarized showing their broad scope.