Ring-Closing Olefin Metathesis of 3,3′-(D-Glycopyranosylidene)bis(1-propene) Compounds as a Route to Anomeric Spiro Sugars

Abstract

New peracetylated 3,3Ј-(D-glycopyranosylidene)bis(1-propene), prepared from peracetylated anomeric sugar dihalides and allyltributyltin in excess under UV irradiation conditions (AIBN, ca. 35°C), lent themselves to ring-closing olefin metathesis in the presence of Grubbs' catalyst (6 mol %) to afford the corresponding peracetylated spiro[1,5-anhydro-D-glycopyranositol-1,4Ј-cyclopent-1Ј-enes] (D-gluco: 81%, D-manno:

Stereocontrolled Access to Higher Sugars (Non-1-en-4-ulopyranosyl Derivatives) and Glycomimetics [3-(β-D-Glycopyranosyl)-1-propenes and(3Z)-4,8-Anhydro-nona-1,3-dienitols]

“…More mobile minor compounds (1.4 mg, R f ϭ 0.52 and 2 mg, R f ϭ 0.47) formed in this experiment were not characterised (see below, the ''one-pot'' synthesis of 10). [67,68] One-Pot Synthesis of 10: Bromochloro -glucopyranosylidene 1 (222.5 mg, 0.5 mmol), allyltri-n-butyltin (330 mg, 0.31 mL, 1 mmol, 2 equiv.) and AIBN (6 mg) were dissolved in deoxygenated benzene (5 mL) and the solution was poured into a quartz tube and stirred under an argon atmosphere for 2 h before exposure to UV light (no filter).…”

“…After removal of the white solid by filtration and concentration of the liquid phase under vacuum, the residue was applied to a column of silica gel eluted with ethyl acetate/petroleum ether (1:3, then 1:2.5 then 1:2 v/v) as the mobile phase. After first obtaining 1,3,4-tri-O-acetyl-2,6-anhydro-5,7,8,9-tetradeoxy--lyxo-nona-5,8-dienitol [68] (9 mg, 6% yield, R f ϭ 0.52, ethyl acetate/petroleum ether 1:2) and an unidentified product having only three acetyl groups [68] (12 mg, R f ϭ 0.47, ethyl acetate/ petroleum ether 1:2), the desired β--glucopyranosyl compound 10 was collected (101 mg, 55% yield), followed by a minor amount of compound 7 (3 mg, 1.5% yield). On NMR examination, no α-anomer of 10 could be detected.…”

“…The organic phase, washed with water (2 ϫ 8 mL), dried (MgSO 4 ), and concentrated under vacuum, afforded a solid (200 mg, 111%) corresponding to 12, of high purity as determined by 1 H NMR spectroscopy (300.13 MHz). Column chromatography with ethyl acetate/petroleum ether 1:2 first afforded trace amounts of a bis-C,C-allyl compound [68] (10 mg, 5% yield), and then 12 (112.6 mg), which crystallized from diethyl ether/petroleum ether (107 mg, 57% yield), m.p. 100Ϫ101°C.…”

Anomeric Spiro-Annulated Glycopyranosides: An Overview of Synthetic Methodologies and Biological Applications

“…Anomeric 3,3 0 -(glycopyranosylidene)bis(1-propene) (e.g. 1) could be readily converted into the spiro-cyclopentene derivatives 2 via ring-closing metathesis using Grubbs I catalyst from acetylated D-gluco-, D-manno-, or D-galacto-configured precursors (e.g., 1) [4] or Grubbs II catalyst from the benzyl-protected D-gluco-or D-galacto-configured bis-propenes (e.g., 1a) toward the corresponding spiro compounds (e.g., 2a) [5] (Scheme 1).…”

Stereoselective synthesis of C-ketosides by sequential intramolecular hydrogen atom transfer–intermolecular allylation reaction

“…2 A number of synthetic procedures have been reported by several groups, 3 in many cases inspired by processes developed for the preparation of the closely related and more extensively studied C-glycosides. 4 However, the use of radical reactions for the synthesis of C-ketosides has, somewhat surprisingly, received very little attention, apart from a few products prepared by the reductive denitration of 1-nitro-C-glycosides with n-Bu 3 SnH and acrylonitrile, 5 the reaction of sugar dihalides with allyltri-n-butyltin, 6 and recently, through the diastereocontrolled Norrish-Yang photocyclization of 5,9-anhydro-1,4-dideoxy-deco-2,3-diuloses. 2b Radical reactions have also been used for the synthesis of C-glycosides of neuraminic acids.…”