A stereocontrolled intramolecular cycloaddition – sigmatropic rearrangement approach to a tricyclo[7.4.01,6.01,10]tridecane precursor for (±) gascardic acid
Keyword(s):
A general intramolecular Diels–Alder anionic oxy-Cope strategy for the synthesis of tricyclic skeletons and its application to the preparation of the gascardic acid precursor 21 is described. In situ generation of the appropriate cyclopentadiene 9 by isomerization (Et3N) afforded the [4+2] adduct directly or with EtAlCl2 as catalyst. The requisite potassium salt of the 1,5 diene 16 rearranged with concomitant epimerization at 67 °C to the fused ring ketone 18. Selective allylic oxidation and reduction provided 21. Key words: Diels–Alder, oxy-Cope, sesterterpene, synthesis, cycloaddition.
Stereo- and Regioselectivity of Pd0/InI-Mediated Allylic Additions to Aldehydes and Ketones. In situ Generation of Allylindium(III) Intermediates from N-Acylnitroso Diels—Alder Cycloadducts and 1-Amino-4-acetoxycyclopentenes.
