New Derivatives of Levoglucosan by Tandem Epoxide Allyl Alcohol Rearrangement‐Cuprate Cross‐Coupling

Abstract

Keywords: 1,6-Anhydro sugars / Chiral building blocks / Branched sugars / Č erný epoxide / Gilman cuprates / Epoxide rearrangement / Vinyl tosylate cross couplingThe alkylated allyl alcohols 6a, 7, and 8 (R = Me, Et, nBu) were formed in the reaction of the Č erný epoxide 3 with the Cyano-Gilman cuprates. The one-pot reaction was initiated by base-catalyzed epoxide allyl alcohol rearrangement to compound 5, followed by unprecedented vinyl tosylate crosscoupling with the cuprates, to form the alkylation products 6a, 7, and 8. The allyl alcohol 6a was transformed into a

Synthesis of the Aliphatic Subunit of the Macrolide LL‐Z 1640‐2 via Vasella Ring Opening of a 6‐Iodo‐4‐deoxy‐D‐mannose

“…Iodoalkene 6 (1.2 g, 60%) was isolated as a colorless liquid after distillation at reduced pressure. 1 (5S)-1-((4R,5S)-5-Allyl-2,2-dimethyl-1,3-dioxolan-4-yl)-5-(tertbutyldimethylsilyloxy)hex-2-yn-1-ol (7) n-Buthyllithium (1.6 M in hexane, 0.45 mL, 0.5 mmol) was added slowly at -608C to the solution of (S)-isopropyldimethyl(pent-4-yn-2-yloxy)silane (5) [23] (90 mg, 0.5 mmol) in dry THF (20 mL). The reaction mixture was stirred for 15 min at -608C.…”

“…Purification by silica gel column chromatography (CH 2 Cl 2 /methanol 98:2) gave ketone 9 (8 mg) as a colorless oil (80%). 1 …”

“…MS (70 eV) m/z (%): 422 (2) [M] þ , 407 (19) [M -CH 3 ] þ , 268 (8) [M -CH 4 SO 3 -C 3 H 6 O] þ , 235 (100) [M -CH 4 SO 3 -C 3 H 6 O -CH 4 O] þ , 69 (8) [C 3 H 6 O] þ . (4S,5S)-5-Allyl-2,2-dimethyl-[1,3]dioxolane-4-carbaldehyde(4)…”

Production and purification of crystallized levoglucosan from pyrolysis of lignocellulosic biomass

“…It has several properties that make it an attractive chemical building block. 1 These properties include chirality, hydroxyl groups at the C-1 anomeric center position and the primary hydroxyl group at C-6, which are protected internally, in addition to the 1,6-anhydro bridge that can be opened during any reaction stage under mild acidic conditions 1,2 to produce fragments with the correct relative and absolute configuration and functionality. This allows them to be incorporated into chemical synthesis schemes.…”

Preparation and formation mechanism of levoglucosan from starch using a tubular furnace pyrolysis reactor

“…An important aspect of carbohydrates pyrolysis (such as glucose, starch, and cellulose) is the formation of 1,6-anhydro-␤-dglucopyranose (levoglucosan, LG), as primary degradation product [10][11][12]. Levoglucosan can be utilized in the synthesis of chiral polymers such as non-hydrolysable glucose polymers and many new compounds [13][14][15]. Levoglucosan is often used as a chemical tracer for biomass burning in atmospheric chemistry studies [16][17][18], particularly with respect to airborne particulate matter.…”