Crocetin dialdehyde

A range of polyenes has been prepared from crocetin dialdehyde and various benzylidenephosphoranes. Among labelled compoimds synthesized using ylides are [2- C]abscisic acid, methyl /ranj -[10- C]retinoate, and trcois-[10- CJretinol. ... 

Reactions at Benzylic Positions. - The catalytic oxidation, using a cobalt bromide catalyst, of 2,5-dimethylthiophen to the dialdehydeof 3-methyl-2-ethylthiophen to 2-acetyl-3-methylthiophen and l-(3-methyl-2-thienyl)-ethyl acetate, of the four isomeric methyl acetothienones to the corresponding acetylthiophencarboxylic acids, and of 2-acetoxymethylthio-phen to thiophen-2-carboxylic acid has been reported. The Wittig reaction between 2- and 3-thenyltriphenylphosphonium salts and crocetin dialdehyde has been used for the synthesis of carotenoid analogues with terminal thiophen rings. ... 

Further examples have appeared of the use of epoxides as the source of the base in olefin synthesis, among them the synthesis of crocetin dialdehyde (1) shown in Scheme 2, Additional polymeric Wittig reagents have been described and used in olefin synthesis. ... 

Recently the application of sulphone coupling was reported for the preparation of lycopene (31) [6]. Geranyldiethylamine (21) was converted into geranylsulphone (22) by reaction with ethyl chloroformate and sodium chlorophenylsulphate. Treatment of 22 with BuLi, crocetin-dialdehyde (536), acetic anhydride and base led to the C4o-disulphone 23 with a di-cis configuration. Reduction with disodium dithionite gave (all- )-lycopene (31) (Scheme 5). 

---