Plant growth regulators in Eucalyptus grandis. V. Synthesis of the G-regulators

Abstract

Problems associated with earlier synthetic approaches to the G-regulators have been overcome by the use of the Mannich reaction in aprotic media. Under these conditions the Mannich base formed from the reaction of 1,3-diketones and aldehydes is stabilized by internal hydrogen bonding and can be isolated in high yield. In aqueous acid rapid elimination occurs to give the 2-methylene 1,3-diketones, which first enolize then add oxygen to generate the G-regulator structure. The steric limitations of the reactions are examined.