5-Alkenyl resorcinols

Several series of resorcinol derivatives have been found in wheat, rice, rye and triticale. These include 5-alkyl resorcinols and pairs of isomeric 5-alkenyl resorcinols (n = 17, 19,21,23,25), accompanied by smaller amounts of 5-(2 -oxoalkyl)-, 5-(4 -hydroxyalkyl), 5-(2 -hydroxyalkenyl)-resorcinols and 5,5 -(alkadiyl)diresorcinols (Figure 7.52) (Suzuki et al. 1999). Whole wheat grains contain some 300-1200mg/kg total resorcinols that are concentrated in the bran (22-26 g/kg for durum wheat). Comparatively low levels... 

Figure 2 Two-dimensional TLC of homologous alkenyl resorcinols. (From Ref. 34, by permission of Elsevier Science Publishers.)...

Resorcinols. RhCl, 3H,() catalyzes isomerization of m-alkenyl-1,3-cyclohexa-ncdionc derivatives to resorcinols.1... 

At higher concentrations, simple phenols are toxic substances that block oxidative phosphorylation. They also exhibit nephrotoxic effects and can act as co-carcinogens. Some alkyl and alkenyl derivatives of phenol, catechol and resorcinol may cause allergic dermatitis. 

The term alkyhesorcinols is used collectively for the group of 5-alkyl, 5-alkenyl, 5-alkadienyl and minor 5-(2-oxoalkyl) and 5-(2-oxoalkenyl) derivatives of resorcinol (benzene-l,3-diol, 10-1). The resorcinol substituents have straight chains with an odd number of carbon atoms. The most common substituents have 13 to 29 carbon atoms. 

Toxic 5-alkatrienyl, 5-alkadienyl, 5-alkenyl and 5-alkyl resorcinols, collectively known as cardol, occur in the cashew nutshell liquid (CNSL), also known as cashew shell oil, a natural resin found in the honeycomb structure of the cashew nutshell. It is a byproduct of cashew nuts processing (see Section 8.2.6.1.6). A typical solvent-extracted CNSL contains 15-20% of cardol. The main components are (8Z,llZ)-pentadeca-8,ll,14-trien-l-yl (10-1), (8Z,llZ)-pentadeca-8,ll-dien-l-yl, (8Z)-pentadeca-8-en-1-yl and pentadecyl derivatives. 

Isomerization of o>-alkenyl-substituted ( clohexane-l,3-dione enol derivatives using rhodium trichloride trihydrate provides a convenient entry to a variety of resorcinol derivatives. ... 

---