Myrtenol synthesis

Recently in our laboratories, we were able to prepare a pair of crystalline enantiomeric cannabinoids (compounds 32 and 33) which could be recrystallized to absolute enantiomeric purity. Their synthesis is based on myrtenol, which can be obtained in both enantiomeric forms. 

Myrtenol (203 X = CH2OH) may be obtained most efficiently from the more stable secondary allylic alcohol (+)-trans-pinocarveol (30 enantiomer) via bromination with PBra to the rearranged bromide (203 X = CH2Br) [(30) (203 X = CH20H)/85 15] ester thermolysis and isomerization-oxidation were less effective, and the direct acid-catalysed isomerization was not observed. Intramolecular cyclization of (206), which is readily synthesized via trifluoroacetic anhydride cyclization of 4-methylcyclohex-3-enylacetic acid to (186), affords (207) which is cleaved to (208 X = NH2) in a synthesis of ( )-a-... 

Bornanes substituted at C-10 can be made by rearrangement of myrtenol (336) esters this results in a fairly rapid synthesis of apocamphanecarboxylic acid (337).30"... 

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