Angular alkylation of 2-carboethoxytricyclo[5.2.1.02,6]decadienone and its implications for the skeletal integrity

Control elements in dynamically determined selectivity on a bifurcating surface

The mechanism and the nature of the dynamically determined product selectivity in Diels-Alder cycloadditions of 3-methoxycarbonylcyclopentadienone (2) with 1,3-dienes was studied by a combination of product studies, experimental kinetic isotope effects, standard theoretical calculations, and quasiclassical trajectory calculations. The low-energy transition structures in these reactions are structurally balanced between [4pi(diene) + 2pi(dienone)] and the [2pi(diene) + 4pi(dienone)] modes of cycloaddition. The accuracy of these structures and their bispericyclic nature is supported by the experimental isotope effects. Trajectories passing through these transition structures can lead to both [4pi(diene) + 2pi(dienone)] and [2pi(diene) + 4pi(dienone)] cycloadducts, and the mixture of products obtained varies with the structure of the diene. The factors affecting this selectivity are analyzed. The geometry of the transition structure is a useful predictor of the major product, but the selectivity is also guided by the shape of the energy surface as trajectories approach the products and by how trajectories cross the transition state ridge.

Structure-activity relationships of sandalwood odorants: synthesis and odor of tricyclo beta-santalol

In a series of structure-odor relationship investigations the synthesis of a new tricyclic beta-santalol derivative is described. The product of a multistep synthesis appears in an olfactive evaluation more or less odorless, may be slightly creamy but definitely with no sandalwood odor. This modification with a bulky aliphatic bridge in the neighborhood of the quaternary C3-atom demonstrated the sensitivity of sandalwood odor on the structure of beta-santalol analogues.