Cycloaddition of Cyclopentadiene to 3-Deoxy-1,2:5,6-di-O-isopropylidene-α-d-erythro-hex-3-enofuranose. Synthesis and Representative Chemistry of 1,6-Anhydro-2,3-dideoxy-β-d-glycero-hex-2-enopyran-4-ulose (“Isolevoglucosenone”)

Abstract

Treatment of D-glucose-derived alkene 4 with cyclopentadiene in the presence of a Lewis acid results in the formation of cycloaddition products 8-11. Evidence is presented to show that these 1,6-anhydro sugar-cyclopentadiene adducts do not arise from rearrangement of 4 to isolevoglucosenone (5) followed by cycloaddition but are the result of Lewis acid-catalyzed rearrangement of alkene 4 to acyclic dienophile 12 followed by addition of cyclopentadiene. Major cycloadduct 8 has been utilized as a source of the enantiomerically pure carbocycles 14-25 by manipulation of the alkene and ketone functions and cleavage of the 1,6-anhydro bridge. In the absence of diene, alkene 4 undergoes rearrangement to enone 5 in 32% yield. Reaction of 5 with several dienes results only in the formation of "bottom-face" adducts 10,11, 28, and 29, and conjugate addition of either HN(3) or Me(3)COOH is found to be completely stereoselective to afford 30 and 31, respectively. Subsequent manipulation of azide 30 leads to precursors of several naturally occurring 2-amino-2,3-dideoxy sugars.

One‐Pot Stereoselective Double Intramolecular Oxymercuration: Synthesis of Four Isomers of an Unsymmetrical Bis‐Tetrahydrofuran Ring System

“…Hydrogenation of the resulting double bond in the presence of Raney Ni in ethanol at 40 psi gave the reduced product, the spectral and analytical data of which were in good agreement with reported values. [21] Selective deprotection of the 5,6-O-isopropylidene group and treatment of the resulting diol with NaH and TsCl afforded the epoxide. Copper-catalyzed epoxide ring-opening with allylmagnesium bromide in the presence of CuCN furnished the alcohol 7 in 84 % yield (Scheme 2).…”

An Aza Analogue of iso‐Levoglucosenone: Synthesis and Application of a New Building Block for Imino Sugars

“…As found [16,17] for iso-levoglucosenone 4, the 1,6-anhydro bridge effectively blocks the top face of the enone and NaBH 4 attacks exclusively from the less-hindered face of the enone. 2D-NOESY Spectroscopic analysis of the derived acetate (Ϯ)-10 suggests the syn-arrangement of the acetate group with respect to CH 2 ϪO group, as the hydrogen atom at the CHOAc group shows a weak coupling to the aromatic hydrogen atoms, but not to the CH 2 group of the anhydro bridge.…”

“…[15] The structure of 3 is reminiscent of another building block often used in the synthesis of natural products, the well-known iso-levoglucosenone 4. [16] iso-Levoglucosenone 4 and its isomer levoglucosenone [17] have been chosen as starting compounds in many syntheses over the years because the functionality is confined in a structurally biased rigid bicyclic framework. Because of the 1,6-anhydro bridge, there is no need for protecting groups at the anomeric carbon atom or the primary hydroxy group at C-6.…”

The Molecular Structure of 1,2:5,6-Di-O-isopropylidene-3-O-toluenesulfonyl-α-D-glucofuranose

“…Interestingly, in subsequent reactions the replacement of the tosyl leaving group against the resulting functional group proceeds under inversion of the configuration of the respective carbon atom C-3 (Walden-inversion) in most of the cases [4]. In addition, side reactions like eliminations were observed as well [5].…”