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The total synthesis of (+/-)-powelline (13 linear steps in an overall yield of 6%) and (+/-)-buphanidrine (14 linear steps and a 6% overall yield) and has been achieved using a novel approach to the crinane skeleton. An organocatalytic oxidative coupling allowed direct construction of the key quaternary carbon-to-aryl bond in high yield allowing rapid access to the target alkaloids.

(R)-3-Amino-2-[1-(2-hydroxyethoxy)ethyl]quinazolin-4(3H)-one 10 was prepared in 62% yield without the need for chromatography and O-cinnamoylated; reaction with lead tetra-acetate gave aziridine 12 as a single diastereoisomer in quantitative yield which was converted into the β-amino acid ester 15 corresponding to overall enantioselective addition of ammonia to the double bond of cinnamic acid.

In this paper we report the development of a stereoselective IMDA approach to the phytotoxic polyketides (±)-solanapyrones A and B. The stereoselectivity of the key IMDA cycloaddition was optimized by investigating a range of 2,8,10-dodecatrienoic acid derivatives. This established that use of the Weinreb amide led to the desired exo -selectivity and also facilitated construction of the pyrone moiety. A novel approach to the installation of the C-3 formyl group in solanapyrone A is also described.