Racemic 3-methyl-1-pentene was synthesized in threcs ste1) s from sec-butyl hroniide in an over-all yield of 12%) wit'h the pyrolysis of a. butyrate as the final step. Opticallj-active d-: 3- inet, h!. ll-peritene, the simplest optically active olefin, with [a]:+ X3. 49",\ vas prepared iri foiir steps in: in ovc, r-all yicld of? Of;, from active amyl alcohol, with the Ipmlysis of the butyrate as the final strp.