Abstract
A series of cycloalkylidene fulgides have been synthesized using β,γ-unsaturated diesters, instead of the usual α,β-unsaturated diesters. A study of their photochromic properties revealed that an increase in the cycloalkylidene ring size caused a subsequent decrease in the formation of the closed form from the open form.
Key words
photochromic - fulgide - fulgimide - electrocyclic reactions - microwave
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8 The observation of the migration of the double bond was also reported then.
9 Compound 10 was obtained in 40% yield and 8 in 9% yield, respectively.
10 As determined from crude 1 H NMR of the reaction mixture.
11 Attempts to obtain the cyclooctylidene succinic diester resulted in the self-condensed product from the cyclooctanone, which was only determined from crude 1 H NMR and not isolated. The cyclopentanone used to obtain 11 also tends to afford the self-condensed product quite readily.
12 This was to ensure the complete formation of the diacid and to maximize yield. Yields of synthesized fulgides were much lower when this step was omitted.
