4-Octene-l,8-diol

Compared to the anodic oxidation of Z-4-octene-l,8-diol (80%, Table 8) its oxidation with pyridinium dichromate in dimethyl formamide gave as the best chemical alternative only 65 % diacid Nickel peroxide oxidation under mild conditions (1.3 eq. peroxide, 25 °C, 1 M NaOH) led to 45% hydroxy acid 75, whereas under more vigorous conditions (3 eq. peroxide, 80 °C, 1 M NaOH) maleic acid was formed ... 

In the same year the biotransformation of these monoterpenes by B. cinerea in model solutions was described by another group [41]. Although the major metabolites found were co-hydroxylation compounds, it is important to note that these authors only identified the -isomers in the extracts and that some new compounds were detected that were not described by the previous group, Fig. (9). Geraniol (20) was mainly transformed to (2 ,5 )-3,7-dimethyl-2,5-octadiene-l,7-diol (53), ( )-3,7-dimethyl-2,7-octadiene-l,6-diol (54) and (2 ,6 )-2,6-dimethyl-2,6-octadiene-1,8-diol (43), nerol (14) to (2Z,5 )-3,7-dimethyl-2,5-octadiene-1,7-diol (55), (Z)-3,7-dimethyl-2,7-octadiene-l,6-diol (56), and (2E,6Z) 2,6-dimethyl-2,6-octadiene-1,8-diol (47). Furthermore a cyclisation product (57) was formed which was not previously described. Finally citronellol (4) was converted to trans- (60) and cw-rose oxide (61) (a cyclisation product not identified by the other group), ( )-3,7-dimethyl-5-octene-l,7-diol (58), 3,7-dimethyl-7-octene-l,6-diol (59) and ( )-2,6-dimethyl-2-octene-1,8-diol (34). 

Figure 4.1. Principal monotepenes in grape and wine. (1) The cis- and fnms-linalool oxide (5-ethenyltetrahydro-a,a,5-trimethyl-2-furanmethanol) (furanic form) (2) lin-alool (3,7-dimethyl-l,6-octadien-3-ol) (3) a-terpineol (a,a,4-trimethyl-3-cycloexene-1-methanol) (4) cis- and fnms-ocimenol [(E- and Z-)2,6-dimethyl-5,7-octen-2-ol] (5) cis- and fnms-linalool oxide (6-ethenyltetrahydro-2,2,6-trimethyl-2H-pyran-3-ol) (pyranic form) (6) hydroxycitronellol (3,7-dimethyloctane-l,7-diol) (7) 8-hydro-xydihydrolinalool (2,6-dimethyl-7-octene-l,6-diol) (8) 7-hydroxygeraniol [( )-3,6-dimethyl-2-octene-l,7-diol] (9) 7-hydroxynerol [(Z)-3,6-dimethyl-2-octene-l,7-diol] (10) cis- and fnms-8-hydroxylinalool [(E- and Z-) 2,6-dimethyl-2,7-octadiene-l,6-diol] ...

Figure 4.1. (Continued) (11) Ho-diendiol I (3,7-dimethyl-l,5-octadiene-3,7-diol) (12) endiol (3,7-dimethyl-l-octene-3,7-diol) (13) Ho-diendiol II (3,7-dimethyl-l,7-octadiene-3,6-diol) (14) citronellol (3,7-dimethyl-6-octen-l-ol) (15) nerol (Z), geraniol (E) (3,7-dimethyl-2,6-octadien-l-ol) (16) neroloxide (17) 2-exo-hydroxy-l,8-cineol (18) 1,8 -cineol (19) wine lactone (20) cis- and /ram-1,8-terpin (21) p-menthenediol I (p-menth-l-ene-7,8-diol) (22) ( )-geranic acid (3,7-dimethyl-2,6-octadienoic acid) (23) (/. )-2,6-dimethyl-6-hydroxyocta-2,7-dicnoic acid (24) (E- and Z)-sobrerol or p-menthenediol II (/>menth-l-ene-6,8-diol) (25) cis- and trans-rose oxide (26) triol (2,6-methyl-7-octene-2,3,6-triol) (27) hotrienol [(5 )-3,7-dimethylocta-l,5,7-trien-3-ol] (28) myrcenol (2-methyl-6-methylene-7-octen-2-ol).

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