A convergent stereocontrolled synthesis of [3-(14) C]solanesol.

In this communication, we report the synthesis of ~5 mCi of [3-(14) C]solanesol (1) prepared from ethyl [3-(14) C]acetoacetate and (all-E)-octaprenyl bromide (2) in four steps, with a specific radioactivity of 19.83 mCi/mmol and with a chemical/stereochemical and radiochemical purity of ≥ 95%. (Figure ). Position 3 of the chain was selected for (14) C labelling because of the metabolic stability of this position. Unlabelled (all-E)-octaprenyl (18) (Scheme ) necessary for this work was prepared via a convergent iterative 'allyl-allyl' coupling approach of precursors easily derived from readily available inexpensive starting materials.(1)

Two-directional ring-opening cross-metathesis.

Two-directional ring-opening cross-metathesis of a range of cyclic alkenes with a variety of electron deficient alkenes has been accomplished; it was found that the process is quite general and gives complete selectivity for the E,E-dienes, making this a very useful and high-yielding protocol for two-directional chain synthesis.

Two-directional cross-metathesis.

Two-directional cross-metathesis of a range of alpha,omega dienes with a variety of electron deficient alkenes has been accomplished. It was found that the process is quite general and gives complete selectivity for the E,E-dienes, making this a very useful and high yielding protocol for two-directional chain elongation.

A two-directional approach to the anatoxin alkaloids: second synthesis of homoanatoxin and efficient synthesis of anatoxin-a.

Total syntheses of the potent neurotoxins, environmental hazards, and biochemical probes anatoxin-a and homoanatoxin have been achieved from a common intermediate using a combined two-directional synthesis-tandem reaction strategy which includes key advances in oxidative desymmetrisation, tandem Michael-intramolecular Mannich cyclisations and a new method for deprotection of N-tosyl anatoxin-a.