Hept-2-enono-l,4-lactone

As discussed in Sect. 3.4, the synthon 20 was prepared from the dibromo-heptonolactone, which in turn was obtained from the cheap commercially available D-g(ycero-D-gM/o-heptono-l,4-lactone (Table 1). The other isomeric dibro-moheptonolactones shown in Table 1, which were prepared from the heptonates, obtained from chain extension of o-mannose and o-galactose, respectively, were also converted into unsaturated bromodeoxyheptonolactones. Finally, we obtained 2-0-acetyl-7-bromo-3,7-dideoxy-D-x7(o-hept-2-enono-l,4-lactone and the corresponding D-/yxo-isomer by the Kiliani extension of o-gulose. These substrates were all cyclized to cyclopentane lactones, stereoisomers of 65 [98]. 

Penta-Me 2,3,5,6,7-Penta-O-methyl-D-Siiabmo-hept-2-enono-l,4-lactone C12H20O7 276.286 Mp 80°. [a] -5 (MeOH). [a] +21 (CCI4). 

Tetra-O -benzoyl-3-deoxy-D-flra6iwo -hept-2-enono-l, 4-lactone, D-149... 

Tetra-O-benzoyl-3-deoxy-D-/yxo-hept-2-enono-l,4-lactone, D-150... 

G. Casiraghi, L. Colombo, G. Rassu, and P. Spanu, Synthesis of enantiomerically pure 2,3-dideoxy-hept-2-enono-1,4-lactone derivatives via diastereoselective addition of 2-(trimethyl-siloxy)furan to D-glyceraldehyde and D-serinal-based three-carbon synthons, Tetrahedron Lett. 30 5325 (1989). 

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