Octafluorocyclopentene, reaction

Reactions of lithium derivatives of thiophene with octafluorocyclopentene... 

The most widely used method for the preparation of perfluorocyclopen-tene-containing DTEs is based on the reactions of lithium derivatives of thiophene with octafluorocyclopentene (98KGS927, 99IZV979, 99JP183). This method is used for the assembly of photochromic products from components indifferent to butyllithium or for the formation of the core of the molecules for their subsequent functionalization. This approach is suitable for the synthesis of both symmetrical and unsymmetrical photochromes. 

The reaction of 2,5-disubstituted 3-furyl bromides with butyl-lithium and octafluorocyclopentene in dry tetrahydrofuran (THF) at —78°C gave bis(furyl)ethenes 82 (06JMC4690). Photochrome 83 (05JOC10323, 06EJ03105) (29-46% yield) and a series of its derivatives 84 (55-65%) containing different substituents at position 6 of the ben-zofuran ring were synthesized from 3-bromo-2-methyl-1-benzofuran (08JPP(A)146). 

The reaction of allyl alcohol with octafluorocyclopentene and the subsequent Claiscn rearrangement are complete within 2 hours at 25 C, giving the rearranged 2-allylheptafluorocy-clopenlanone (6).x... 

Bis(trifluoromethy])trioxide, CF3OOOCF3, adds to only one equivalent of octafluorocyclopentene to give us and trans isomers of a mixed tnfluoromethyl ether-tnfluoromethylperoxide (equation 13) A radical mechanism is involved [37], unlike in the electrophilic reactions of CF3OOCl [32]... 

The synthesis of a novel compound l,2-bis(2-methylbenzo[/ ]furan-3-yl)-perfluorocyclopentene 92 was realized by reaction of octafluorocyclopentene with 3-lithiated 2-methylbenzo[3]furan, which was generated by the treatment of 2-methyl-3-bromobenzo[ ]furan with -BuLi at —78°C in THE, as can be seen in Equation (86) <2005JOC10323>. 

With the aim of synthesizing new photochromic dihetarylethenes, viz., 5-substituted l,2-bis(thieno[3,2-Z)]thiophen-3-yl)perfluorocyclopentenes 181a-c, 2-(ben-zothiazol-2-yl)-6-bromo-5-methylthieno[3,2-fc]thiophene (182) was subjeeted to metallation. A mixture of lithium derivatives produced by this reaction was treated with octafluorocyclopentene (CsFg) (2000MI1, 2001IZV107). 

The University of Kyoto, the MCPT research group, and Yamada Chemical developed an effective method for the synthesis of photochromic diarylethenes through the generation of heteroaryHithiums and subsequent reaction with octafluorocyclopentene... 

Figure 11.26 Synthesis scheme of photochromic diarylethenes. (a) Generation of heteroaryllithiums through the Br-Li exchange reaction of heteroaryl bromides and (b) the reaction of octafluorocyclopentene with heteroaryllithium.

Reactions of Lithium Derivatives of Thiophene with Octafluorocyclopentene.. 521... 

Abstract The review considers the synthesis and structures of photochromic products, in which hetaryl substituents are separated by the centtal 1,2-perfluorocyclopentene moiety. It was also briefly presented main methods for synthesis of octafluorocyclopentene and its reactivity. Among methods used for the synthesis of the photochromes, the reactions of hthium derivatives of thiophene, benzothiophene, and other heterocyclic compounds with octafluorocyclopentene, 1,2-dichlorohexafluorocyclopentene, and their analogues are described. Another general method for the synthesis of dihetarylethenes, considered in the review, is based on the McMurry reaction involving the initial... 

Some characteristic reactions of OFCP, including those used for the synthesis of photochromic DHE, are considered below. Octafluorocyclopentene, like the most part of other fluorinated olefins, is a pronounced electrophile characterized by the interaction with various nucleophiles according to the addition-elimination type reactions. For selected reports on the reaction of perfiuorocyclopentene 1 or the 1, 2-dichloroanalog with 0,N,S,P-nucleophiles, see [32, p. 4222 and references cited therein]. 

On the whole, the materials of this brief section indicate that octafluorocyclopentene is an accessible (for at least research purposes) product, whose reactivity was studied in rather detail. The variation of the reaction conditions makes it possible to obtain the diverse mono- and disubstituted derivatives of this product containing substituents both at the double bond of cyclene and in the aUyl positions. 

The main method for the preparation of perfluorocyclopentene DHE used in the majority of studies is the reaction of the lithium derivatives of thiophene with octafluorocyclopentene [43 5, 41]. The photochromic products are thus assembled from the components indifferent to butyllithium or the molecule backbone is formed for further functionalization. This approach allows one to synthesize both symmetrical and unsymmetrical photochromes. 

Yamada S, Konno T, Ishihara T, Yamanaka H (2005) Reaction of octafluorocyclopentene with various carbon nucleophiles. J Fluorine Chem 126 125-133. doi 10.1016/j.jfluchem.2004.10.047... 

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