Synthesis of conjugated diene pheromones and related compounds

A method for preparing a conjugated diene according to Formula I:

• the method comprising:
• (i) forming a reaction mixture comprising:
• an olefin according to Formula V:
• an aldehyde according to Formula IV:
• and
• a metathesis catalyst comprising a transition metal and (a) a first carbene ligand, (b) an N-heterocyclic carbene ligand, and (c) a phenylphosphine ligand, a tri(isopropoxy)phosphine ligand, a dimethylsulfoxide ligand, an acetonitrile ligand, or a pyridine ligand;
• (ii) maintaining the reaction mixture under conditions sufficient to form a metathesis product according to Formula III:
• and
• (iii) combining the metathesis product according to Formula III with a phosphonium ylide according to Formula II:
• under conditions sufficient to form the conjugated diene according to Formula I, wherein:
• R1 is —OR1a, —C(O)OR1b, or —C(O)H,
• R1a is C1-6 acyl or H,
• R1b is H or C1-6 alkyl,
• R2 is C3-12 alkyl or C1-2 alkyl,
• R3a, R3b, R4a, and R4b are independently H or C1-6 alkyl,
• each R5 is independently optionally substituted C6-C10 aryl, and
• subscript x is an integer ranging from 6 to 12 or an integer ranging from 1 to 5.