Cyclopentane Glucose

The base-mediated intramolecular alkylation of glucose derivatives provides highly functionalized cyclopentanes in good yield and without any of the expected side reactions (Equation 60) <2000TL5507, 2001T4729>. 

The inexpensive, commercially available D-g/ycero-D-gw/o-heptono-1,4-lactone ( glucoheptonolactone since it is prepared from D-glucose) is the precursor for the 2,7-dibromo-2,7-dideoxy-D-g/ycm -D-/afo-heptono-1,4-lactone (1) (Scheme 13) which, via the unsaturated lactone 2a and radical induced carbocyclisation, could be transformed into the crystalline dihydroxy cyclopentane lactone 4a in high yield (Scheme 14). This short and efficient synthesis of the cis-fused cyclopentane lactone provides easy access to a chiral synthon which might be modified stereospecifically for many purposes. Such... 

The volatiles produced by sugar degradation can make an important contribution to flavour. Pyrolysis of glucose at 300 °C allowed 56 compounds to be identified, the main product being l,4 3,6-dianhydroglucopyranose.567 More than 100 volatiles were separated when glucose was heated at 250 °C for 30 min in air or in nitrogen 4-hydroxy-2-pentenoic acid lactone, 1-(2-furyl)propane-l,2-dione, and 3-methyl-cyclopentane-1,2-dione were identified as new products.568... 

Trehazolamine. Chiara has described a synthesis of trehazolamine, the aglycon of trehazolin, a powerful inhibitor of trehalase, wherein a pinacol cyclization provided the necessary cyclopentane framework (Eq. 3.2) [17]. Thus, treatment of the tetrabenzyl-protected keto aldehyde, derived from D-glucose, with Sml2 furnished the two cis diols exclusively as a 1 1 mixture of isomers in excellent yield (>90%) [18]. Previous studies of five-membered ring formation mediated by SmE have also reported good cis/trans selectivity, presumably due to the intervention of a samarium chelate. 

Simple organic compounds o-tcrphenyl, toluene, 3-mcthyl hexane, 2,3-dimethyl ketone, diethyl ether, isobutyl bromide, ethylene glycol, methyl alcohol, ethyl alcohol, glycerol, glucose. As droplets only m-xylene, cyclopentane, n-heptane, methylene chloride. 

Methods for synthesizing anisomycin and pentenomycin, ° and the chemistry and biological transformations of bleomycin and phleomycin have been reviewed.D-Ribo-furanosyl and -pyranosyl derivatives of iV-methyl-iV-nitroso-urea have been prepared as analogues of streptozotocin [2-deoxy-2-(JV-methyl-A -nitrosoureido)-D-glucose] they were reported to be more active against LI 210 leukaemia in mice and less toxic than the parent antibiotic. Likewise N- 2-chloroethyl)-iV-nitrosoureido derivatives of cyclopentane tetrols (35) and cyclohexane tetrols (36) have been synthesized for comparison with streptozotocin. ... 

The synthesis and base-mediated intramolecular alkylation/cyclization of 6-deoxy-6-iodo-2,3 4,5-di-0-isopropylidene-D-glucose leading to the polyfun-ctionalised cyclopentane 145 has been reported. The reduction and acetylation of this compound to generate a 4a-carfca-a-D-arabinofuranoside derivative was also described. ... 

D-Glucose has been converted to the bicyclic lactone 71, in which a key 3-carbon chain homologation is effected via aldehyde allylation. This lactone is a known precursor of acdnobolin, and this synthesis thus constitutes a formal total synthesis. ° The cyclopentane-fused 5-lactone 72, a potential prostaglandin synthetic intermediate, has been prepared from levoglucosan.3t... 

Oxime ethers derived from hydroxy aldehydes, upon conversion to their phenyl thionocarbonate esters, undergo radical cyclizations resulting in the formation of carbocycles. For example, an oxime ether obtained from D-glucose is converted into its phenyl thionocarbonate ester at C-5 and, upon heating in benzene in the presence of tributyltin hydride, affords cyclopentanes in 93% yield as a 62 38 mixture of two diastereomers (eq 7). In general, only low to modest stereoselectivity between the newly formed stereocenters is observed in a number of substrates examined. 

A biosynthetic study of aristeromycin using labelled precursors has found that the cyclopentane ring is generated by C-C bond formation between C-2 and C-6 of D-glucose the authors propose oxidation at C-5 or C-4 occurs leading to a cyclopentenone derivative. 

Free radical cyclization reactions have seen further developments this year. A mixture of cyclopentanes 8-10 (precursors of isoprostaglandins) have been obtained via fragmentation of thionocarbonate 7 derived from D-glucose (sugar numbering shown) (Scheme 3). ... 

As an example of the use of this methodology in total synthesis, the zirconocene-promoted ring contraction was the key step in the route to (+)-epiafricanol (100) reported by Paquette et al. [78]. Vinyl pyranose 95, obtained from D-glucose in 12 steps, was treated with Cp2Zr in toluene at -78°C and then with boron trifluoride etherate at room temperature, affording vinyl cyclopentane 96 in a 63% yield. Conversion of 96 to ketone 97 with periodinane as the oxidant in the presence of sodium bicarbonate and addition of the lithium derivative to 4,4-dimethyl-5-iodo-l-pentene 98 gave rise to 99. Cyclization of 99 by RCM followed by cyclopropanation finally afforded the desired product 100 (Scheme 3.39). 

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