Myrtenal

On oxidation with chromic acid in acetic acid solution, myrtenol yields a corresponding aldehyde, which has been termed myrtenal. This body has the following characters —... 

Myrtenal, C oH, 0, is an aldehyde found in the oil of Perilla nankin-ensis, associated with perillic aldehyde. It is also formed by the reduction of myrtenol, an alcohol of the formula CjpH,gO, occurring in oil of myrtle leaves. Myrtenal has the following characters —... 

Helquist et al. [129] have reported molecular mechanics calculations to predict the suitability of a number of chiral-substituted phenanthrolines and their corresponding palladium-complexes for use in asymmetric nucleophilic substitutions of allylic acetates. Good correlation was obtained with experimental results, the highest levels of asymmetric induction being predicted and obtained with a readily available 2-(2-bornyl)-phenanthroline ligand (90 in Scheme 50). Kocovsky et al. [130] prepared a series of chiral bipyridines, also derived from monoterpene (namely pinocarvone or myrtenal). They synthesized and characterized corresponding Mo complexes, which were found to be moderately enantioselective in allylic substitution (up to 22%). 

In determination of the enantiomeric purity of aliphatic primary amines, the use of (S-aminoalcohols and ot-amino acids 1R(—)-myrtenal as a derivatising agent has been tested.1... 

Possible racemisation of imines, derivatives of amino acids and R(—)-myrtenal, has been examined by Dufrasne et al.1 After 72 h, no significant effect on chiral purity was observed. For imines being derivatives of chiral primary amines and the a-substituted 8-keto-aldehydes, no evidence of epimerisation has been indicated by the NMR measurements.3 For a series of imines, being derivatives of amino acids or amino acid esters and (R)-BINOL reagents, Chin et al.5 have tested the possibility of epimerization under experiment conditions. It was shown that R S ratio has changed only slightly, and after 24 h, the difference was lower than 10%. 

New chiral auxiliaries for nucleophilic reactions have been prepared from 5-hydroxy-l-tetralone <2001TA2605> and myrtenal <2001TA3095> and their use in diastereoselective reactions has been evaluated. It was found that both the tetralone- <2003EJ0337, 2003JOC6619> and the myrtenal- <2003TA3225, 2005TA1837> derived 2-acyl-l,3-oxathianes reacted diastereoselectively with nucleophiles (Equations 60 and 61). 

In 2003, Torre and his co-workers prepared new terpene-aromatic hybrids 47 in high yields in the reactions of cobalt-coordinated propargylic compounds, derived from commercial (7iJ)-myrtenal, with a variety of aromatic compounds (Equation (23)). Interestingly, any terpene-aromatic hybrids are not produced from propargylic compounds without cobalt coordination. 

This Mulheim chemistry has been highlighted by the discovery of the highly enantioselective hydrovinylation of styrene to produce chiral 2-phenyl-1-butene in 95.2% ee for a 10 kg-scale reaction (Scheme 60) (132). The Ni catalyst is very reactive and contains the unique chiral dimeric aminophosphine ligand derived from (R)-myrtenal and (S)-1-phenylethylamine. Computer simulations suggest that in this chiral Ni complex, the phenyl substituent of the chiral phenylethyl group acts as a windshield wiper across the catalytically active metal center. This... 

The photo-oxidation of PE sensitized by DC A in homogeneous solution followed by reduction of the reaction mixture with sodium sulfite solution gave the ene product pinocarveol 14 and the non-ene products myrtenal 15, epoxide 16 and aldehyde 17, as shown in Fig. 21. The ene product and the non-ene products have been proposed to be derived from the energy-transfer and electron-transfer pathways, respectively [177-181], The product distributions in acetonitrile is given in Fig. 21. 

Solladie-Cavallo, A. Balaz, M. Salisova, M. Welter, R. New 1,3-oxafhianes derived from myrtenal synthesis and reactivity. /. Org. 

Hardie J., Isaacs R., Pickett J. A., Wadhams L. J. and Woodcock C. M. (1994) Methyl salicylate and (-)-(lR,5S)-myrtenal are plant-derived repellents for the black bean aphid. Aphis fabae Scop. (Homoptera Aphididae). J. Chem. Ecol. 20, 2847-2855. 

---