Stereocontrolled synthesis of (−)-allosamizoline using D-glucosamine as a chiral template

An enantiospecific synthesis of allosamizoline

“…Crystallisation of the residue from ether at 0 "C gave the title oxime ether as a white crystalline solid (21. 5 mmol) in dichloromethane (25 cm3) at 0 °C was added 0phenyl chlorothioformate (2.0 g, 11.8 mmol) and pyridine (4 cm3, 50 mmol). The stirred solution was allowed to warm to room temperature overnight under an atmosphere of nitrogen after which it was poured into dilute HCl(50 cm3) and extracted with ethyl acetate (3 x 50 cm3).…”

“…Flash chromatography ( 10-2074 ether in dichloromethane) gave the title compound as an oil which slowly crystallised at 0 "C (840 mg, 60%), m.p. 5 (b) Oxadidinone 21. The benzyl carbamate obtained in (a) above (640 mg, 2.72 mmol) was dissolved in thionyl chloride ( 5 cm3) and heated to reflux under an atmosphere of dry nitrogen for 2 h. The reaction mixture was allowed to cool and the thionyl chloride removed under reduced pressure.…”

Making natural products from renewable feedstocks: back to the roots?

“…Therefore, GlcNHAc and GlcNH 2 are ideal templates for the synthesis of stereochemically demanding natural products. Several groups have utilized GlcNH 2 (201) in this respect for the synthesis of (À)-allosamizoline ((À)-231), [356][357][358][359][360][361] a bacterial pseudo-aminosugar with chitinase inhibitory activity. [362][363][364][365] For this potentially biomimetic approach, 366 two main routes emerged for the crucial intramolecular ring closure to form the cyclopentane ring (Scheme 36).…”

Synthesis of (–)-Allosamizoline, the Pseudoaminosugar Moiety of Allosamidin, a Chitinase Inhibitor

“…An (14). Ozone was bubbled through a solution of 12 (11.67 g, 22.6mmol) in CH 2 CI 2 -MeOH (10: 1, 660ml) at -30°C for 12h.…”