An improved synthesis of a potent serotonin agonist 1a and its novel derivative 1b is described, making use of a Claisen rearrangement whose unstable phenolic product is methylated and isomerized in situ. This method may be of general use in the synthesis of o- methoxylated phenethylamine derivatives. The synthesis also includes an unusual, one pot demethylation/primary alcohol bromination with boron tribromide.