Showing papers on "Intramolecular reaction published in 1979"
TL;DR: Isomeric 2′- and 3′-O-t-butyidimethylsilylribonucleoside derivatives undergo interconversion by a first-order equilibration reaction.
Abstract: Isomeric 2′- and 3′-O-t-butyidimethylsilylribonucleoside derivatives (2) and (3) undergo interconversion by a first-order equilibration reaction. This intramolecular reaction takes place particularly readily in methanol solution and in the presence of base.
57 citations
TL;DR: In this paper, a synthesis of methyl 2,3-di-Obenzyl-7,8-dideoxy-4-O-methylthiomethyl-D-glycero- and L-Gluco-Oct-7-enopyranoside (11 and 12) has been achieved.
Abstract: A synthesis of methyl 2,3-di-O-benzyl-7,8-dideoxy-4-O-methylthiomethyl-D-glycero- and L-glycero-α-D-gluco-oct-7-enopyranoside (11 and 12) has been achieved by the reaction of methyl 2,3-di-O-benzyl-4-O-methylthiomethyl-α-D-gluco-hexodialdo-l,5-pyranoside (9) with vinylmagnesium bromide; the stereochemistry at C-6 was established by degradation of 12 to the enantiomer of a known heptose derivative. Olefin 12 was converted, in six steps, into a mixture of dialdose derivatives 18 and 19 from which methyl glycosides 21 and 20, respectively, were prepared and shown to have the desired trans-decalin structure. The stereochemistry at C-7 in glycosides 20 and 21 was established by nmr spectroscopy.An intramolecular reaction involving the methylthiomethyl function has been observed and shown to give rise to O-methylene derivatives.
17 citations
TL;DR: In this paper, a dye-sensitized photo-oxygenation of trimethylsilylphenyldiazomethane produced phenyl trimethyl silyl ketone and trimethyl Silyl benzoate; the latter may be formed from the sily l substituted carbonyl oxide via intramolecular reaction.
Abstract: Dye-sensitized photo-oxygenation of trimethylsilylphenyldiazomethane produced phenyl trimethylsilyl ketone and trimethylsilyl benzoate; the latter may be formed from the silyl substituted carbonyl oxide via intramolecular reaction.
7 citations
TL;DR: In this paper, a synthesis of methyl 2,3-di-Obenzyl-7,8-dideoxy-4-O-methylthiomethyl-D-glycero- and L-Gluco-Oct-7-enopyranoside (11 and 12) has been achieved.
Abstract: A synthesis of methyl 2,3-di-O-benzyl-7,8-dideoxy-4-O-methylthiomethyl-D-glycero- and L-glycero-α-D-gluco-oct-7-enopyranoside (11 and 12) has been achieved by the reaction of methyl 2,3-di-O-benzyl-4-O-methylthiomethyl-α-D-gluco-hexodialdo-l,5-pyranoside (9) with vinylmagnesium bromide; the stereochemistry at C-6 was established by degradation of 12 to the enantiomer of a known heptose derivative. Olefin 12 was converted, in six steps, into a mixture of dialdose derivatives 18 and 19 from which methyl glycosides 21 and 20, respectively, were prepared and shown to have the desired trans-decalin structure. The stereochemistry at C-7 in glycosides 20 and 21 was established by nmr spectroscopy.An intramolecular reaction involving the methylthiomethyl function has been observed and shown to give rise to O-methylene derivatives.
01 Jan 1979
TL;DR: The potential efficiency of intramolecular catalysis, as measured by the effective concentration of the catalytic group, depends strongly on the mechanism, and generalisations are relevant to understanding of the efficiency of catalysis by enzymes.
Abstract: The potential efficiency of intramolecular catalysis,as measured by the effective concentration of the catalytic group, depends strongly on the mechanism. Nucleophilic catalysis can be very efficient indeed, but intramolecular general base, and probably general acid catalysis also, are intrinsically much less efficient. These generalisations are relevant to our understanding of the efficiency of catalysis by enzymes.