273934-61-5Relevant articles and documents
Reciprocal donor acceptor selectivity (RDAS): A new concept for matching donors with acceptors
Fraser-Reid, Bert,Lopez, J. Cristobal,Radhakrishnan,Mach, Mateusz,Schlueter, Urs,Gomez, Ana,Uriel, Clara
, p. 1075 - 1087 (2007/10/03)
Lemieux's extensive work on replacement reactions at the anomeric center helped to establish the fact that the O-2-protecting group of a donor exerts powerful control over stereoselectivity in glycoside coupling reactions. This manuscript shows that the O-2-protecting group of a donor also exerts powerful, indeed sometimes total, control over regioselectivity in glycosidation of diols. The latter acceptors also exhibit preferences over the donor, thereby providing evidence for the concept of reciprocal donor acceptor selectivity (RDAS). The latter concept is put to the test by simultaneously presenting an acceptor diol with equivalent amounts of two donors, in the hope of achieving double differential glycosidation leading to one-pot assembly of a trisaccharide. When the pair of donors did not conform to RDAS principles the reaction did not proceed beyond a dissacharide. However, when the pair was RDAS sanctioned, a single trisaccharide (out of four possibilities) was obtained.
Evidence for efficient unpromoted regioselective reactions of vicinal and non-vicinal diols
Fraser-Reid, Bert,Anilkumar, Gopinadhan Nair,Nair, Latha G.,Radhakrishnan,Cristobal Lopez,Gomez, Ana,Uriel, Clara
, p. 123 - 130 (2007/10/03)
A 1965 publication from Angyal's laboratory reported that the cis-vicinal diol group of tetra-O-benzyl myo-inositol reacted regioselectively, sometimes exclusively, with acylating agents at the equatorial OH, but with alkylating agents at the axial OH. Recent reports by Fraser-Reid and coworkers showed that such selectivities were also found for the trans-1,3-diol of tetra-O-benzyl myo-inositol, as well as the C2-C4 hydroxyls of a di-O-allyl mannopyranoside. In addition, the latter workers reported that regioselectivities could be extended to glycosidation reactions. Thus, n-pentenyl ortho ester (NPOE) and 2-O-acyl n-pentenyl glycoside (NPGAC) donors reacted preferentially, if not exclusively, at the equatorial OH, whereas 2-O-alkyl counterparts (NPGALK) gave mixtures, usually with major glycosidation occuring at the axial OH. The present manuscript examines several vicinal diols, and reports that the NPOE and (NPGAC) donors frequently react at only one of the two hydroxy groups in good yield, whereas the corresponding benzylated donor (NPGALK) is less discriminating, and frequently gives lower yields. In a key experiment to examine the basis of the selectivity, it was found that the highly hindered C3 OH of 4,6-O-benzylidene methyl α-D-altropyranoside was selectively glycosylated with NPOE in 92% yield, thereby establishing that the glycosidation preference is not due to steric hindrance.
Regioselective mannosylation routes to the antigenic myo-inositol component of Mycobacterium tuberculosis
Anilkumar,Gilbert, Mark R.,Fraser-Reid, Bert
, p. 1993 - 1997 (2007/10/03)
A differentially protected derivative of myo-inositol with free hydroxyl groups at C6 and C2 is regioselectively mannosylated at C2, and subsequently at C6 with the same or a different donor to give the dimannosylated inositol antigenic core of Mycobacterium tuberculosis. Deacetylation now frees C1 for phosphorylation. (C) 2000 Elsevier Science Ltd.
Targeted glycosyl donor delivery for site-selective glycosylation.
Anilkumar,Nair,Fraser-Reid
, p. 2587 - 2589 (2007/10/03)
[reaction: see text]n-Pentenyl ortho esters (NPOEs) and n-pentenyl glycosides (NPGs) are interconvertible glycosyl donors which are activated by reaction with halonium ions. In a series of cyclic syn-1,3-diols, NPOEs have been found to specifically glycos
