The Carbonates and Thiocarbonates of Carbohydrates

Cyclic limonene dicarbonate as a new monomer for non-isocyanate oligo- and polyurethanes (NIPU) based upon terpenes

“…11 Unlike traditional PU, NIPUs exhibit improved thermal stability, because there are no thermally labile biuret and allophanate groups incorporated in the PU backbone. 12 There exists two synthetic routes for preparing five-membered cyclic carbonates: (i) trans esterification of diols with alkylene carbonates, 13,14 and (ii) catalytic carbonization of epoxides with CO 2 . Today, the second route is attracting considerable attention because CO 2 , known as one of the sources of global warming, is used as a feed stock to produce materials with a low carbon foot print.…”

Nucleotides. V. Purine Ribonucleoside 2',3'-Cyclic Carbonates. Preparation and Use for the Synthesis of 5'-Monosubstituted Nucleosides*

“…Carbonates, usually as the fiveor six-membered cyclic esters, have been used extensively as protected intermediates in synthesis of carbohydrates (Hough et al, 1960). A 2,3-cyclic carbonate of ribofuranose has been prepared from a 1,5-disubstituted derivative and used for the synthesis of an a nucleoside (Wright et al, 1958).…”

“…Carbonates of carbohydrates have most commonly been prepared by use of phosgene or of chloroformic esters (Hough et al, 1960). Diphenyl carbonate was reported recently by Hough and co-workers (1962) to be useful for the preparation of hexitol carbonates by transesterification.…”

“…In view of the evidence described below, that the ester interchange reactions with diphenyl carbonate are acid catalyzed, the product obtained from acidic detritylation of 5'-O-tritylinosine 2',3'-carbonate (II) could conceivably be the 3',5'-carbonate, even though six-membered cyclic carbonate esters are predicted to be less stable than the corresponding five-membered rings (Hough et al, 1960). To investigate this possibility, and to determine the utility of ribonucleoside 2',3'-cyclic carbonates for the synthesis of nucleoside 5'-phosphates, the inosine carbonate was phosphorylated in pyridine solution with ¡3-cyanoethyl phosphate by the procedure of Tener (1961).…”

Nucleophilic reactivity of anions associated with a lipophilic proton cryptate, [H+c(1.1.1,C14)]

“…The reactivity of an ion pair A+X~in a condensed phase reaches the highest values when at least two fundamental conditions are achieved: (1) a good solubility in non-polar media; (2) a large cation-anion separation.1 These conditions are especially fulfilled by onium quaternary salts, bearing long and/or bulky alkyl chains,1 and by multidentate ligands which surround metal cations giving rise to lipophilic macrocations.2 3Within the latter species, lipophilic cryptates are of particular interest, since they probably represent the best model of "solvent-separated ion pair". 3,4 In a series of papers we have studied the anionic reactivity of lipophilic cryptates3,5,6 compared with that of quaternary onium salts7,8 and complexed crown ethers. 4 We have also reported9 the synthesis of [H+C-(1.1.1,C14)]Y" cryptates 1, following a route which directly affords the proton cryptated species.…”