2 research outputs found
Fragmentation of carbohydrate anomeric alkoxy radicals: a new synthesis of chiral 1-halo-1-iodo alditols
10 pages, 3 tables, 2 schemes.-- PMID: 14673851 [PubMed].-- Supporting information (52-page PDF file) available at: http://www.wiley-vch.de/contents/jc_2111/2003/f5294_s.pdfTreatment of 1,2-fluorohydrins, 1,2-chlorohydrins, 1,2-bromohydrins, and 1,2-iodohydrins of the D-gluco, D-galacto, D-lacto, L-rhamno, D-allo, L-arabino, 3-deoxy-D-gluco, and 3,4-dideoxy-D-gluco families of carbohydrates with the (diacetoxyiodo)benzene/iodine system afforded 1-fluoro-1-iodo, 1-chloro-1-iodo, 1-bromo-1-iodo, and 1,1-diiodo alditols, respectively, in excellent yields. The reaction was achieved by radical fragmentation of the C1bond;C2 bond, triggered by the initially formed anomeric alkoxy radical, and subsequent trapping of the C2-radical by iodine atoms. This methodology is compatible with the stability of the protective groups most frequently used in carbohydrate chemistry. The potential utility of these 1-halo-1-iodo alditols as chiral synthons was evaluated by their transformation into alk-1-enyl iodides and in the Takai E-olefination reaction.This work was supported by the Investigation Programs nos. PPQ2000-0728, BQU2000-0650, and BQU2001-1665 of the Direcci贸n General de
Investigaci贸n Cient铆fica y T茅cnica, Spain. C.R.-F. thanks the Direcci贸n General de Universidades e Investigaci贸n del Gobierno de Canarias for
a fellowship
Fragmentation of carbohydrate anomeric alkoxyl radicals. A new synthesis of chiral 1-halo-1-iodo alditols
Treatment of 1,2-fluorohydrins, 1,2-chlorohydrins, 1,2-bromohydrins, and 1,2-iodohydrins of the D-gluco, D-galacto, D-lacto, L-rhamno, D-allo, L-arabino, 3-deoxy-D-gluco, and 3,4-dideoxy-D-gluco families of carbohydrates with the (diacetoxyiodo)benzene/iodine system afforded 1-fluoro-1-iodo, 1-chloro-1-iodo, 1-bromo-1-iodo, and 1,1-diiodo alditols, respectively, in excellent yields. The reaction was achieved by radical fragmentation of the C1C2 bond, triggered by the initially formed anomeric alkoxy radical, and subsequent trapping of the C2-radical by iodine atoms. This methodology is compatible with the stability of the protective groups most frequently used in carbohydrate chemistry. The potential utility of these 1-halo-1-iodo alditols as chiral synthons was evaluated by their transformation into alk-1-enyl iodides and in the Takai E-olefination reaction