Circular dichroism properties of (3S,5R)-cis- and (3S,5S)-trans-3,5-dimethylvalerolactones

Asymmetric Synthesis of Optically Active 3-Substitutedδ-Valerolactones Using Lipase in Organic Solvents

“…Distillation gave 6b as an oil (8.4g, 65%); bp 150-160oC (18mmHg); 1 H-NMR (90MHz) 8: 2.48 (d,1=6.3Hz,4H),3.30 (s,3H),3.63 (s,6H),.1 (m, !H). (7). To a solution of 6b (8.3 g, 44 mmol) in MeOH (50 ml) was added a solution of NaOH (7.0g, 0.18mmol) in water (30m!)…”

“…The R-configuration for ( + )-16 (X=CH 2 Cl) and (+)-17 (X=CH 2 F) was established by the lactone chirality rule. 7 l In other words, these lactones exhibited a positive Cotton effect at 224 nm in CD spectra, which indicates the negative dihedral angle of …”

“…It has been revealed in our previous report 2 bl that the reaction was retarded by large groups at C-3. Taking into account the bulkiness of the substituents for lipase to assume full catalytic activity, and the versatility of the products as chiral building blocks, 3-chloromethylglutaric anhydride (4), 3-fl.uoromethylglutaric anhydride (5) and 3-methoxyglutaric anhydride (7) were chosen as acid anhydride substrates. Since 3-methyl-6-valerolactone has been found to constitute a chiral fragment in several natural products, 4 and 5 affording their haloderivatives are of synthetic significance.…”

Asymmetric synthesis of optically active 3-substituted .DELTA.-valerolactones using lipase in organic solvents.

“…3-Fluoromethylglutaric anhydride (5). Starting from 3 (3. 3-Methoxyglutaric anhydride (7). To a solution of 6b (8.3g, 44mmol) in MeOH(50ml) was added a solution of NaOH (7.0g, 0.18mmol) in water (30ml) with ice-cooling.…”