Ethyl(benzothiazol‐2‐ylsulfonyl)acetate: A New Reagent for the Stereoselective Synthesis of α,β‐Unsaturated Esters from Aldehydes.

Abstract

Carboxylic acid esters Q 0530Ethyl(benzothiazol-2-ylsulfonyl)acetate: A New Reagent for the Stereoselective Synthesis of α,β-Unsaturated Esters from Aldehydes. -Sulfone (III) is used for the synthesis of α,β-unsaturated esters from aldehydes. Under mild conditions in the presence of DBU, (E)-isomers are obtained as the major products. For the aliphatic aldehydes n-hexanal (IIIg) and citronellal (VII), (Z)-isomers are preferentially isolated. When NaHMDS in refluxing THF is used, the (E)-isomer (Vg) can be isolated as the main component. A complex mixture of intractable products is identified in the case of cinnamaldehyde (IIIj). The reaction of phenylacetaldehyde (X) is non-regiospecific and affords predominantly the β,γ-unsaturated ester (XII). -(BLAKEMORE*, P. R.; HO, D. K. H.; NAP, W. M.; Org. Biomol. Chem. 3 (2005) 8, 1365-1368; Sch. Chem., Univ. Leeds, Leeds LS2 9JT, UK; Eng.) -S. Adam 37-080

A Novel Convergent Synthesis of the Antiglaucoma PGF2α Analogue Bimatoprost

“…17b Additionally, the appropriately functionalized aldehydes with steric encumbrance should afford trans alkenes as the only products of Julia reaction. 18 In the chemical structure of bimatoprost (10a) the carbon 17 position in the o-chain is substituted by a phenyl ring. We envisaged that combining the sulfone 15 (Scheme 2) with the a-hydroxy protected aldehyde 16a should give the mixture of hydroxy sulfones 17a, which in a few simple steps could be transformed to bimatoprost 10a.…”

“…DAMS ET AL. 18 h at room temperature and then quenched with crushed ice (25 g). The resulting mixture was portioned between hexanes (25 ml) and H 2 O (50 ml).…”