Deoxy‐nitrosugars. 11^th Communication. Reactions of 1‐C‐nitroglycosyl halides and 1‐C‐nitroglycosyl sulfones with dialkyl‐phosphite anions: Nucleophilic attack vs. single‐electron transfer

Abstract

Treatment of the chloro-nitro-ribofuranose 7 with KPO(OMe)2 gave the 0-amino phosphate 8 (5%) and the nitrile 9 (62%). Compound 9 was also obtained by the reaction of 8 with KPO(OMe),, and its structure was established by X-ray analysis. Treatment of the chloro-nitro-mannofuranose 10, the bromo-nitro-ribofuranose 14, or the bromo-nitro-mannofuranose 16, respectively, with the K or Na salt of HPO(OMe)2 lead also to 0-amino phosphates and nitriles. The (1-C-nitrog1ycosyl)phosphonate 22 was obtained (21 %) together with the nitrile 21 (5 1 %) from the chloro-nitro-mannofuranose 10 and KPO(OEt)2. The reaction of the I-C-nitroglycosyl sulfone 25 (NO2-group endo) with KPO(OEt), gave the (I-C-nitroglycosy1)phosphonate 22 (61 %) and the nitrile 21 (1 1 YO), whilst the anomeric sulfone 26 (NO,-group exo) gave 22 (15%) and 21 (58%). In the presence of [18]crown-6, a mixture of the anomers 25 and 26 gave the (I-C-nitroglycosy1)phosphonate 22 in 67% yield together with 21 (13%). These findings are rationalized as the result of a competition between a nucleophilic attack of the dialkyl-phosphite anions on the NO2-group leading ultimately to the nitrile 21 and a single-electron transfer reaction leading to the (1-C-nitroglycosy1)phosphonate 22.

Dramatic solvent and concentration dependence in the reaction of (anthracen-9-yl)methanamines with suitable electron-deficient acetylenes

“…Competitive reactions are those in which a compound reacts simultaneously through more than one pathway to give different products. Several competitive reactions including one electron transfer versus nucleophilic attack and unimolecular versus bimolecular reactions are reported in literature . A few photochemical and gas‐phase reactions also follow several parallel reaction pathways.…”

Synthesis of Benzimidazoles by Phosphine‐Mediated Reductive Cyclisation of ortho‐Nitro‐anilides

“…The torsion angle C(1)ÀN(7)ÀC(8)ÀO (9) is À 7.38, with the C¼O group turned away from to the phosphine imide moiety, the torsion angle C(8)ÀN(7)ÀC(1)ÀC(2) being À 175. 38. In solution in CDCl 3 , 11 forms an intramolecular NH ··· N¼P H-bond, as evidenced by the chemical shift of the NH signal, resonating at 9.70 ppm.…”

The Last Fortress of Tin's Tyranny – Protodenitration of Nitroalkanes

“…Firstly, there are only a few reports on the attempted reduction of primary nitroalkanes, and the outcome varies from case to case. In 1995 Witczak reported a fascinating reduction of dinitro derivative 254, where both primary nitro groups and xanthate were reduced simultaneously with tributyltin hydride (49), yielding derivative 255 (Scheme 11). [116] Scheme 9.…”