New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline- 2,4(1H,3H)-dione compounds

• Oldřich Paleta,
• Karel Pomeisl,
• Stanislav Kafka,
• Antonín Klásek and
• Vladislav Kubelka

Beilstein J. Org. Chem. 2005, 1, No. 17, doi:10.1186/1860-5397-1-17

• annulation of the fluorobutenolide cycle. An analogous Horner-Wadsworth-Emmons synthesis using ethyl (diethoxyphosphoryl)-fluoroacetate prepared from ethyl fluoroiodoacetate has been reported for the preparation of the α-fluoro-α,β-unsaturated acyclic esters and lactones. [14] However, when 1-benzyl-3-butyl

Stereoselective α-fluoroamide and α-fluoro- γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement

• Kenny Tenza,
• Julian S. Northen,
• David O'Hagan and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2005, 1, No. 13, doi:10.1186/1860-5397-1-13

• conditions and resulted in N-(α-fluoro-γ-vinylamide)pyrrolidine products as homochiral materials in 99% de. These products were readily converted to their corresponding α-fluoro-γ-lactones by iodolactonisation and in good diastereoselectivity. Conclusion Molecules which have fluorine at a stereogeneic centre

• fluorinated substrates, to generate α-fluoro-γ-vinyl amides and then α-fluoro-γ-lactones as the end products after iodolactonisation. In 1998 Nubbemeyer[12][13] reported on such aza-Claisen rearrangements using the N-allylproline ester 1 and the N-allylpyrrolidine ether 2 with the acid fluoride of azidoacetic

• amines, to offer an alternative strategy to α-fluorocarbonyl compounds. Such products can be converted to γ-lactones by straightforward iodolactonisation.[14] γ-Lactones are a ubiquitious motif found in many natural product sand they are also useful templates for the synthesis of a wide range of bio

Towards practical biocatalytic Baeyer- Villiger reactions: applying a thermostable enzyme in the gram- scale synthesis of optically- active lactones in a two-liquid- phase system

• Frank Schulz,
• François Leca,
• Frank Hollmann and
• Manfred T. Reetz

Beilstein J. Org. Chem. 2005, 1, No. 10, doi:10.1186/1860-5397-1-10

• well versed in the use of enzymes. Keywords: Baeyer-Villiger oxidation; monooxygenases; two-liquid-phase system; stereoselective catalysis; biocatalysis; Introduction First reported in 1899, the Baeyer-Villiger (BV) reaction of ketones with formation of esters or lactones has become a fundamental and

• the practical biocatalytic preparation of enantiopure lactones based on BVMOs is proposed. Results and Discussion The commercially available rac-bicyclo [3.2.0]hept-2-en-6-one (1) is a common benchmark substrate for BVMOs. It is readily oxidized by CHMO in an enantioselective way and the products of

• after a reaction time of 24 h a conversion of 43% and moderate enantioselectivity for lactones (-)2 and (+)3 (Table 1). Conversion was drastically improved with mutants P1, P2, and P3 to more than 95% under the same whole-cell conditions, which clearly indicates enhanced enzyme activity. Additionally