Asymmetric synthesis of optically active vinyltetrahydrofurans via palladium-catalysed cyclisation of bis(hydroxymethyl)allylic carbonates

Optically active 3-alkyl-3-hydroxymethyl-5-vinyltetrahydrofurans were synthesised from the corresponding methyl or isobutyl carbonates of ω,ω-bis(hydroxymethyl)-α,β-unsaturated alcohols via palladium-catalysed cyclisation. The use of chiral ligands gave the corresponding tetrahydrofuran derivatives, which had er values that ranged from moderate to good.

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N-[(1S,2S)-2-(Diphenylphosphino)cyclohexyl]-N′-(2,3,6,2′,3′,4′,6-hexa-O-acetyl-β-d-cellobiose)ureaC45H57N2O18P[α]D20=-24.8 (c 0.5, CH2Cl2)Source of chirality: the precursor and saccharide (β-d-cellobiose)Absolute configuration: (1S,2S); β-d-cellobiose (1R,2R,3S,4R,5R, 1′R,2′R,3′S,4′R,5′R)

1,3,4,6-Tetra-O-trimethylsilyl-2-deoxy-2-{[2-(diphenylphosphino)benzoyl]imino}-α-d-glucopiranoseC37H58NO5PSi4[α]D20=+41.6 (c 0.5, CHCl3)Source of chirality: saccharide (α-d-glucopiranose)Absolute configuration: α-d-glucopiranose (1S,2R,3S,4R,5R)