Levoglucosenone (LGO), an enantiomerically pure renewable compound, can be efficiently produced from cellulosic wastes by the Furacell process™, a metal-catalyzed flash pyrolysis developped by CIRCA Group. Interestingly Baeyer-Villiger reaction on levoglucocenone provides (S)-γ-hydroxymethyl-α,β-butenolide (HBO) which is a valuable synthon for pharmaceutical, agrochemical and polymer industries. While classical Baeyer-Villiger oxidation uses harmful peroxides such as m-chloroperoxybenzoic acid (m-CPBA), lipases can also be used to run this reaction. By forming peroxide in situ through the oxidation of fatty acid (lauric acid, decanoic acid) or ester (ethyl acetate) with hydrogen peroxide, this lipase-mediated Baeyer-Villiger oxidation avoids the use of peracids in large quantities. Such reactions were rencently performed on cyclic ketones leading to caprolactones with a good yield in 48h, unfortunately, in such conditions, enzyme activity decreased substantially preventing its reuse for further cycles. Herein, we report the efficient synthesis of HBO using a two-step sequence involving a lipase-mediated Baeyer-Villiger oxidation and an acid hydrolysis. In the same fashion, (S)-γ-hydroxymethyl-γ-butyrolactone (2H-HBO) was successfully obtained through a three-step sequence (Baeyer-Villiger, palladium-catalysed hydrogenation and acid hydrolysis). The use of solid buffers in the lipase-mediated Baeyer-Villiger oxidation has proved beneficial in two ways: not only the reaction time and the enzymatic load were both reduced four-fold (from 8 to 2 hours and 464 to 113 U/mmol) to reach conversions ≥ 83%, but solid buffers also kept lipase from denaturation, thus preserving its enzymatic activity and allowing its use for further oxidation cycles.

Chemo-enzymatic synthesis of key intermediates (S)-γ-hydroxymethyl-α,β-butenolide and (S)-γ-hydroxymethyl-γ-butyrolactone via lipase-mediated Baeyer-Villiger oxidation of levoglucosenone

249th National Meeting (2015)

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<br /> Chemo-enzymatic synthesis of key intermediates (S)-γ-hydroxymethyl-α,β-butenolide and (S)-γ-hydroxymethyl-γ-butyrolactone via lipase-mediated Baeyer-Villiger oxidation of levoglucosenone