High-pressure Diels-Alder cycloadditions between benzylideneacetones and 1,3-butadienes: application to the synthesis of (R,R)-(-)- and (S,S)-(+)-Delta8-tetrahydrocannabinol.
High-pressure Diels-Alder reactions of various alkoxy/alkyl-substituted benzylideneacetones with methyl-1,3-butadienes are reported. Activation by high pressure (8-11 kbar) in combination with the mild Lewis acid HfCl(4).2THF allows these reactions to efficiently and regioselectively produce a series of ortho-substituted cyclohexenyl-benzene cycloadducts, that are useful precursors for the expeditious construction of the privileged 6,6-dimethyltetrahydro-6H-benzo[c]chromene skeleton. Application to the synthesis of Delta(8)-trans-THC in both enantiomeric pure forms is based on the successful resolution of selected cycloadduct by the SAMP-hydrazone method.
Ballerini
Eleonora
E
Dipartimento di Chimica, Università degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy.
Minuti
Lucio
L
Piermatti
Oriana
O
D001597:Benzylidene Compounds / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry*; D002185:Cannabidiol / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism
D001597:Benzylidene Compounds; D002070:Butadienes; D002185:Cannabidiol