Enynes fluorinated

Fluonnated ylides have also been prepared in such a way that fluonne is incorporated at the carhon P to the carbamonic carbon Vanous fluoroalkyl iodides were heated with tnphenylphosphine in the absence of solvent to form the necessary phosphonium salts Direct deprotonation with butyUithium or hthium dusopropy-lamide did not lead to yhde formation, rather, deprotonation was accomparued by loss of fluonde ion Flowever deprotonation with hydrated potassium carbonate in thoxane was successful and resulted in fluoroolefin yields of45-S0% [59] (equation 54) P-Fluorinated ylides may also be prepared by the reaction of an isopropyli-denetnphenylphosphine yhde with a perfluoroalkanoyl anhydnde The intermediate acyl phosphonium salt can undergo further reaction with methylene tnphenylphosphorane and phenyUithium to form a new yhde, which can then be used in a Wittig olefination procedure [60] (equation 55) or can react with a nucleophile [6/j such as an acetyhde to form a fluonnated enyne [62] (equation 56)... 

This catalytic tandem carbene addition-bicyclization of enynes has been very recently applied to the synthesis of fluorinated bicyclo[ .0.l]-amino esters.176... 

Alternatively, fluorinated aminoesters with the enyne structure were transformed into a variety of vinyl cyclic amino acid derivatives and related bicydic derivatives via Diels-Alder and oxidation reactions [38] (Sdieme 8.6). 

Scheme 8.6 Enyne metathesis in the synthesis of fluorinated bicyclic aminoesters.

The cross-coupling of alkynylzinc halides or fluorinated alkenylzinc halides with fluori-nated alkenyl iodides allows the preparation of a range of fluorinated dienes or enynes - Functionalized allylic boronic esters can be prepared by the cross-coupling of (dialkylbo-ryl)methylzinc iodide 428 with functionalized alkenyl iodides. The intramolecular reaction provides cyclized products, such as 429 (Scheme 109) ° °. In some cases, reduction reactions or halogen-zinc exchange reactions are observed. 

Additions occur more easily if a carbanion with resonance or inductive stabilization is formed in the addition. Thus, fulvenes are very reactive, vinylsilanes and highly fluorinated alkenes somewhat less so. Styrene, 1,3-dienes, and enynes are more reactive than isolated alkenes, and Grignard reagents may be used to initiate anionic polymerization of styrenes, dienes, and acryhc monomers. Strained alkenes such as norbomenes and cyclopropenes are also more reactive. Examples of additions facilitated by resonance or substitution are shown in Scheme 8. 

Several fluorinated enynes have been prepared by reacting combinations of alkynylzinc chlorides with fluoroalkenyl iodides, or perfluoroalkynylzinc chlorides with alkenyl iodides [20]. 

Several fluorinated enynes (14) have been prepared by the reaction of alkynylzinc chlorides with fluo-roalkenyl iodides (equation 10), and the Pd-catalyzed cross-coupling reactions of aryl fluoroalkanesul-fonates with organozinc reagents have been reported (equation 11... 

An access to aryl-substin aryl halides by C FjOCu wh Alkynes. 1,4-Diyncs j To synthesize enynes (17 exi treated with another alkynt organostannanes is also catah 1,2-Bis(trifluorometkyl followed by reaction of the c Cul, leads to the fluorinated... 

The allenylidene-ruthenium system also appeared as effieient catalyst precursors for enyne metathesis and they were applied to the preparation of fluorinated cyclic amino esters with a 1,3-diene structure allowing Diels-Alder reactions (Scheme 20) [43],... 

Euchikami T, Shibata Y, Grata H (1987) Transition-metal complex catalyzed polylluor-oalkylation. A facile synthesis of fluorine-containing oxiranes and enynes. Chem Lett... 

In the presence of diazo compounds 9, enynes 10 containing a fluorinated amino acid moiety could be transformed into fluorinated alkenyl bicyclo[4.1.0]heptane amino acid derivatives 11 using Cp (Cl)Ru(COD) as the precatalyst (Scheme 5.5) [12], In this process, the in situ-generated catalyst from ruthenium complex and diazo compound completely inhibits RCM of enyne to the profit of cascade alkenyl-ation/cyclopropanation. The Cp (Cl)Ru moiety in ruthenacyclobutane is believed to favor reductive elimination versus expected alkene metathesis. 

Hu CM, Hong F, Xu YY. Synthesis of trifluoromethyl-substituted conjugated enynes including a fluorinated siccayne. J. Fluorine Chem. 1993 64 1-4. 

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