Intramolecular [4+3] Cycloadditions. Towards a Synthesis of Widdrol
摘要:
Certain substituted alkoxyallylic sulfones were alkylated and treated with Lewis acids to produce vinylthionium ions that underwent intramolecular [4+3] cycloaddition reactions with a tethered furan. Manipulation of the cycloadduct led to the synthesis of widdrol. Other attempts to prepare the cycloadducts were made, but none were exceptionally better than the route using vinylthionium ions as intermediates. Interesting aspects of the alkylation chemistry of phenylthio-substituted alkoxyallylic sulfones are detailed as well.
or hydrogen with inversion of the absolute configuration via the two-step sequence consists of Grignard reaction or reduction of the carbonyl followed by pinacol-type rearrangement. This transformation was applied to the total synthesis of the [6-7] fused-ring sesquiterpene widdrol ((±)-9). The stereochemistry of the tertiary alcohol of 9 was specifically controlled by employing a bridge-cleaving method
A TOTAL SYNTHESIS OF (±)-WIDDROL. SYNTHETIC APPLICATION OF THE FORMAL BRIDGEHEAD SUBSTITUTION OF 1-METHOXYBICYCLO[3.2.2]NON-6-EN-2-ONES WITH ALKYL GROUPS
The [6–7] fused-ring sesquiterpene (±)-widdrol has been prepared stereospecifically utilizing the characteristic reactions of the bridged polycyclic compounds derived from 1-methoxy-5-methylbicyclo[3.2.2]non-6-en-2-one.