Showing papers by "J. Cristobal Lopez published in 2014"
TL;DR: Two complementary one-pot, three component synthetic strategies based on copper(I)-catalyzed azide–alkyne cycloadditions (CuAAC) have been developed, which allow the efficient assembly of glycosyl-derived alkynes or azides with highly fluorescent boron–dipyrromethene (BODIPY) cores containing azido or alkyne moieties, respectively.
25 citations
TL;DR: Compounds resulting from ring expansion (oxepanes), ring contraction (tetrahydrofurans), or branched pyranoses, by incorporation of nucleophiles, can be obtained from 6-O-benzyl, 6-hydroxy, or 6-Silyl derivatives, respectively.
Abstract: Novel substrates that combine dicobalt hexacarbonyl propargyl (Nicholas) and pyranose-derived allylic (Ferrier) cations have been generated by treatment of hexacarbonyldicobalt (C-1)-alkynyl glycals with BF3 (.) Et2 O. The study of these cations has resulted in the discovery of novel reaction pathways that have shown to be associated to the nature of O-6 substituent in the starting alkynyl glycals. Accordingly, compounds resulting from ring expansion (oxepanes), ring contraction (tetrahydrofurans), or branched pyranoses, by incorporation of nucleophiles, can be obtained from 6-O-benzyl, 6-hydroxy, or 6-O-silyl derivatives, respectively. The use of a 6-O-allyl alkynyl glycal led to a suitable funtionalized oxepane able to experience an intramolecular Pauson-Khand cyclization leading to a single tricyclic derivative.
19 citations
TL;DR: In this paper, recent developments in the use of promoters for the Ferrier rearrangement of O-, N-, C- and S-nucleophiles with glycals are discussed.
Abstract: Review: recent developments in the use of promoters for the Ferrier rearrangement of O-, N-, C- and S-nucleophiles with glycals; <250 refs.
18 citations
TL;DR: In this paper, the substituent at O-6 in hexacarbonyldicobalt alkynyl glycals plays a pivotal role in directing the outcome of the transformations.
Abstract: Abstract Pyranosidic allylic (Ferrier) cations that share dicobalt hexacarbonyl propargyl (Nicholas) stabilization at C-1, can be easily generated by treatment of hexacarbonyldicobalt alkynyl glycals with BF3·OEt2, and display a remarkable reactivity leading to a variety of products. The substituent at O-6 in these glycals plays a pivotal role in directing the outcome of the transformations. Accordingly, 6-O-benzyl or 6-O-allyl groups cause a series of transformations resulting in the stereoselective formation of oxepanes through a process that involves an initial hydride transfer step from the allyl or benzyl substituent to the Ferrier–Nicholas cation. On the contrary, 6-OH derivatives undergo an overall ring contraction to branched tetrahydrofuran derivatives. 6-O-Silyl derivatives, in the presence of heteroaryl nucleophiles, were transformed into C-3 branched bis-C-C-glycosides, containing two of such molecules.
5 citations