Synthesis of optically active polycyclic compounds by Diels–Alder reactions of (+)-nopadiene
摘要:
4-Oxo-2-cyclopentenylacetate 1 underwent a tandem Diels-Alder reaction with (+)-nopadiene 3 to lead to C-2-symmetric optically active polycyclic ketone 4. All attempts to carry out similar processes with acetoxy ketone 1 and two different dienes, that is, (+)-nopadiene 3 and isoprene 6 or 2,3-dimethyl-1,3-butadiene 7 were unsuccessful. Enantiomerically pure polycyclic ketones 8 and 9 were prepared by Diels-Alder cycloaddition between optically active alpha,beta-unsaturated ketone 5 and dienes 6 and 7. (C) 2004 Elsevier Ltd. All rights reserved.
derivatives, prepared in situ from the corresponding bromoindanones, have been studied. All cycloadditions are regioselective and endo-anti diastereoselective. The best yields were obtained when the Diels–Alderreactions were carried out under high pressure conditions. All new compounds were characterized by their spectroscopic data, in particular by extensive NMR investigations.
4-Oxo-2-cyclopentenylacetate 1 underwent a tandem Diels-Alder reaction with (+)-nopadiene 3 to lead to C-2-symmetric optically active polycyclic ketone 4. All attempts to carry out similar processes with acetoxy ketone 1 and two different dienes, that is, (+)-nopadiene 3 and isoprene 6 or 2,3-dimethyl-1,3-butadiene 7 were unsuccessful. Enantiomerically pure polycyclic ketones 8 and 9 were prepared by Diels-Alder cycloaddition between optically active alpha,beta-unsaturated ketone 5 and dienes 6 and 7. (C) 2004 Elsevier Ltd. All rights reserved.