3,3′-Dideoxytrehaloses via dimerisation of 2-hydroxyglycal esters

Experimental and theoretical study of the conformational, vibrational and magnetic properties of 4,6-di-O-acetyl-2,3-dideoxy-d-threo-hex-2-enopyranosyl ethanesulfonamide

“…The present results suggest that the b anomeric form is the most stable conformation of ESA, indicating that the composition at 298.15 K should be about a 71% in b anomer and about a 29% in a one. It should also be noted that the five stable conformers reported in this work present the o H 5 conformation with C1AO1AC5AC4 dihedral angles around the ideal value of 64° [21] and the acetoxymethyl group at C5 in a pseudo-equatorial position.…”

Sugar-derived building blocks. Part 26.Part 25. See ref. 1. Hydrophilic pyrroles, pyridazines and diazepinones from d-fructose and isomaltulose

“…Preparatively more favorable proved to be the use of 3-chloroperbenzoic acid or singlet oxygen for oxidative ring opening in the furans 3 and 4, since not only the oxidations proceeded cleanly (TLC, 1 H NMR), but due to the slightly acidic conditions no cis ? trans-isomerization occured, allowing the isolation of the cis-hexenediones 6 and 7 in high yields ( > 90%).…”

“…The structural assignment to the cis- (6) and trans-enedione 10 -both were obtained in nicely crystalline form -were based on 1 H NMR data, which are identical except for the chemical shift of the 2H-singlet for the olefinic protons H-3 and H-4: 6.40 ppm for the cis-olefin 6 vs. 7.00 for the trans-isomer 10, in accord with analogous shift differences in the cis/trans-isomers of hex-3-ene-2,5-dione. 17 Saturation of the olefinic double bond in either of the hexenediones 6-11 could be effected catalytically (Ni/H 2 ) yet in some cases, obviously depending on the activity of the catalyst, concomitant hydrogenation of one of the carbonyl groups was also observed.…”

“…7 By contrast, technically viable reaction channels from carbohydrates to nitrogen heterocycles, which would be of similar industrial importance, have not been systematically exploited, some recent investigations on the transformation of sugars into pyridinols 8 and pyrazoles 9 being first endeavors towards this end. In continuation of our efforts to convert cheap, bulk-scale available sugars simply and efficiently into N-heterocycles with inherent hydrophilic substituents, we here detail oxidative conditions that allow the direct conversion of HMF (1) and its Oglucosylated analog 2 into derivatives of 2,5-hexanedione (I) and 4-ketopentanoic acid (II), then to be cyclized with amines, diamines and hydrazine to N-heterocycles of the pyrrole (III), pyridazine (IV) and diazepine type (V) (Scheme 1).…”

Catalytic tin radical mediated tricyclisations. Part 1. Monocyclisation studies †

“…Ferrier rearrangements are usually performed with boron trifluoride-diethyl ether as the Lewis acid catalyst. Photoinduced electron transfer, 22 lithium tetrafluoroborate, 23 ceric ammonium nitrate, 24 iodine, 25 and NIS treatment of 3-Opentenyl glycals 26 have been also been advocated, but only the last two have found wide acceptance. In our experience, zinc chloride gives cleaner products which require less purification, than boron trifluoride-diethyl ether.…”