Octafluorocyclopentene, reaction with lithium derivatives

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. 

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

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 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. 

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). 

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