13942-77-3Relevant articles and documents
Catalytic Enantioselective α,β,γ-Trioxygenation
Chen, Jason S.,Abeykoon, Gayan A.
, p. 6050 - 6053 (2016/01/09)
Applying a catalytic enantioselective aldehyde α-oxygenation condition to an enal substrate led to the discovery of the first α,β,γ-trifunctionalization cascade of enals. Under optimal conditions, a tryptophan-derived imidazolidinone catalyst in fluorinated aromatic solvents provided α,β,γ-trioxyaldehydes in up to 51% isolated yield (average of 80% yield per oxygenation step) and 85:15 er. Substitution at the δ position was tolerated, but not at the α, β, or γ positions. The reaction proceeded through initial TEMPO incorporation at the γ position, and rapid racemization of this intermediate, reversible conjugate addition of water, followed by TEMPO incorporation at the α position to set all three stereocenters with double dynamic kinetic resolution.
Decarbonylation of Unprotected Aldose Sugars by Chlorotris(triphenylphosphine)rhodium(I). A New Descent of Series Approach to Alditols, Deoxyalditols, and Glycosylalditols
Andrews, Mark A.,Gould, George L.,Klaeren, Stephen A.
, p. 5257 - 5264 (2007/10/02)
Unprotected Cn aldose sugars are cleanly decarbonylated by 1 equiv of chlorotris(triphenylphosphine)rhodium(I) in 1-24 h at 130 deg C in N-methyl-2-pyrrolidinone solution to give the corresponding Cn-1 alditol in about 75-95percent yields.This technique represents a useful variation on traditional carbohydrate "descent of series" reactions.The procedure is quite general and also works on a number of aldose derivatives, such as deoxy sugars, N-acetylated amino sugars, and disaccharides, providing convenient small-scale syntheses of deoxyalditols, (acetylamino)deoxyalditols, and glycosylalditols, respectively.The reactions proceed with complete retention of stereochemistry, the only side products observed being a few percent of the Cn lactones and the Cn-2 alditol.Attempts to make the reactions catalytic have not yet been very successful.
The Biosynthesis of Thiamine. Syntheses of -1-Deoxy-D-threo-2-pentulose and Incorporation of this Sugar in Biosynthesis of Thiazole by Escherichia coli Cells
David, Serge,Estramareix, Bernard,Fischer, Jean-Claude,Therisod, Michel
, p. 2131 - 2138 (2007/10/02)
Non-growing, washed cells of Escherichia coli, depressed for the synthesis of thiamine, were incubated in the presence of -1-deoxy-D-threo-2-pentulose (9) in a medium containing the pyrimidine moiety of thiamine, L-tyrosine, and glucose.The thiamine thus biosynthesized was extracted and cleaved to give 5-(2-hydroxyethyl)-4-methylthiazole (HET) which was examined as the trifluoroacetate derived by electron-impact mass spectrometry.The distribution of the label in the fragments indicated that the pentulose (9) was a precursor of the C5-chain of HET without C-C bond cleavage.Several routes to 1-deoxypentuloses are described.Condensation of 2,4-O-benzylidene-D-threose (23) with trideuteriomethylmagnesium iodide gave the protected 1-deoxypentitols (24) and (25).Brominolysis of the mixed dibutylstannylidenes then afforded -3,4-O-benzylidene-1-deoxy-D-threo-2-pentulose (26), which was converted into the free sugar (9) by acidic hydrolysis. 1-Deoxy-D-erythro-2-pentulose was prepared in similar manner.Condensation of 2-(-methyl)-1,3-dithian with 2,3-O-isopropylidene-D-glyceraldehyde, followed by a C-3 epimerization step also led, after deprotection, to a mixture of -1-deoxy-D-erythro- and -1-deoxy-D-threo-2-pentulose, (5) and (6).
