A Short, Efficient, and Stereoselective Synthesis of Piperine and its Analogues

A quantitative synthesis of piperine from commercially available starting material is presented. The synthesis relies on a stereoselective nucleophilic attack of an in situ generated cuprate onto a cyclobutene lactone. The so-formed aryl-substituted cyclobutene spontaneously undergoes a conrotatory 4π-electrocyclic ring opening to form the 4-aryl pentadienoic acid as a single diastereoisomer. The high-yielding synthesis can be easily modulated on the aryl and on the amide moiety for the synthesis of a wide range of piperine analogues.

Flower Bud Dormancy, ABA Concentration, and Survival during Frost of Jojoba Genotypes under Water Stress

Flower bud dormancy and anthesis patterns, ABA concentration, and bud survival following frost were studied in eight jojoba [Simmondsia shinensis (Link) Schneider] clones grown under two irrigation regimes (water stress and well irrigated). Several clones broke dormancy in the autumn. Anthesis in the field before winter occurred only in one clone (a male) in the well-irrigated treatment. Buds on water-stressed plants broke dormancy earlier than those on well-watered plants, but anthesis in the field occurred later in the year. Buds on water-stressed plants were less affected by a severe frost than those on control plants (43% vs. 10% survival). There were large differences among clones in the amount of frost damage. ABA levels did not correlate with dormancy patterns or with the amount of frost damage. Chemical name used: S-(Z,E)-5-(1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2,4-pentadienoic acid (ABA).