Pergamon Tetrahedron: Asymmetry 9 (1998) 2197–2199 TETRAHEDRON: ASYMMETRY An easy approach to chiral non-racemic 6-(furan-3-yl)-5,6- dihydro-pyran-2-ones Annunziata Soriente, Margherita De Rosa, Patrizia Dovinola, Guido Sodano and Arrigo Scettri ∗ Dipartimento di Chimica, Università di Salerno, 84081 Baronissi (SA), Italy Received 20 April 1998; accepted 22 May 1998 Abstract Chiral non-racemic 6-(furan-3-yl)-pyran-2-one derivatives, key-intermediates in the preparation of compactin, manoalide and cacospongionolide subunits, are easily accessible through a rapid and convenient six-step sequence. © 1998 Elsevier Science Ltd. All rights reserved. The strictly related subunits 1 and 2a,b represent the main structural features of some natural products characterized by important biological activities, such as richardianidins 1 (as regards 1), isolated from the leaves of the toxic plant Cluytia richardiana, manoalide 2 and cacospongionolide 3 (as regards 2a and 2b respectively) two naturally occurring antiinflammatory marine compounds, containing a pyranofuranone moiety which is considered to be the pharmacophoric group. From a chemical point of view, the easy manipulation of the furan and of the pyranone rings allows the ready conversion of the substructure 1 into 2. 4 Therefore, the preparation of compound 1 in both enantiomeric forms represents a main target of our research, devoted to the development of new synthetic sequences leading to chiral manoalide and cacospongionolide analogs. 5 Now we wish to report a new synthesis of chiral 6-(furan-3-yl)-5,6-dihydro-pyran-2-one (+)-1 and (−)-1 through a six-step sequence, whose efficiency and convenience can be mainly attributed to the employment of microwave (MW) irradiation for the achievement of highly selective processes (Scheme 1). The first step involved the generation of the C-5 stereogenic centre by enantioselective aldol con- densation of masked acetoacetic ester 4 in the presence of titanium tetraisopropoxide, as a transition ∗ Corresponding author. E-mail: titti@ponza.dia.unisa.it 0957-4166/98/$ - see front matter © 1998 Elsevier Science Ltd. All rights reserved. PII: S0957-4166(98)00210-9 tetasy 2359 Communication