... Ltd., High Wycombe, Bucks UK. Received 7 June 1988, Available online 16 July 2001. Abstract. Radical cyclisations involving α-acetal methyl centres and2(5 )-furanone and maleate electrophores allow the facile syntheses of spiro- and linear-fused γ-lactone ring systems eg (6), (10), (14) and (19), found in the ginkgolides. ... b H Bhandal, G Pattenden, JJ Russell; see also Tetrahedron Letters, 27 (1986), p. 2299. ...