Synthesis of Fluorinated Analogs of Polyunsaturated Fatty Acid Metabolites (4 HNE, 13 HODE)

Natural halogenated fatty acids: their analogues and derivatives

A comprehensive survey has been made of all fatty acids containing halogen atoms covalently bonded to carbon and which are deemed as naturally occurring. Generally thought to be minor components produced by many different organisms, these interesting compounds now number more than 300. Recent research, especially in the marine area, indicates this number will increase in the future. Sources of halogenated fatty acids include microorganisms, algae, marine invertebrates, and higher plants and some animals. Their possible biological significance has also been discussed

The propargylic route as a short and versatile entry to optically active monofluorinated compounds

Using selected models and appropriate NMR techniques, it has been demonstrated that dehydroxyfluorination in the propargylic position can be highly regio- and stereoselective. The corresponding propargylic fluorides are very useful intermediates for short preparations of stereodefined unsaturated or polyunsaturated compounds with a single fluorine atom in allylic or propargylic position. This strategy offers good means for the synthesis of chiral, nonracemic monofluorinated analogues of natural products.

Extraannular fluorinated calixarenes: regiospecificity of the deoxofluorination reactions of bis(spirodienol) derivatives

A new route for the partial displacement of OH groups of p-tert-butylcalixarene via spirodienol derivatives is described. NaBH(4) reduction of the bis(spirodienone) calixarene derivatives 2a-2c afforded the corresponding bis(spirodienols) 3a-3c in stereospecific fashion. (1)H NMR NOESY spectroscopy indicated that in the case of 2a, the reaction proceeds by attack at the exo face of the two carbonyls (the face located anti to the spiro C-O bond). The spirodienols readily revert to p-tert-butylcalix[4]arene when heated. The reaction of 3a with the deoxofluorinating agent DAST (Et(2)NSF(3)) afforded a mixture of extraannular substituted calixarenes possessing one or two fluoro-substituted dehydroxylated rings. The bisfluorinated calixarene 6a adopts in the crystal a conformation (1,3-alternate) similar to that adopted in solution by the di-dehydroxylated calixarene 6b. An experiment conducted with a selectively deuterated spirodienol derivative indicated that the deoxofluorination reaction involves regiospecific nucleophilic attack at the gamma position of the pentadienol subunit.

Synthesis of new optically active propargylic fluorides and application to the enantioselective synthesis of monofluorinated analogues of fatty acid metabolites

A new approach to obtain optically active unsaturated or polyunsaturated systems with a single fluorine atom in an allylic or propargylic position is reported. Central to this strategy is the high regio- and stereocontrol observed during the fluorination of propargylic alcohols allowing a short and efficient synthesis of 1. Further, simple functional group transformations gave the enals 2 and 3. These three key intermediates were used for the preparation of optically active monofluorinated analogues of fatty acid metabolites.