A convenient synthesis of specifically substituted conjugated dienes via organocopper(I) induced SN2′ reactions. An attractive route to myrcene

Abstract
The paper describes the preparation of a number of symmetrically substituted 1,3‐dienes H2C=C(R)‐C(R)=CH2 (3a‐d) as well as non‐symmetrically substituted 1,3‐dienes H2C=C(R1)‐C(R)=CR2R3 (3e‐i, R ≠ R1) by means of organocuprate induced SN2′ reactions in the esters X‐CH2‐C≡C‐CH2‐X (1, X = MeS(O)O or ToS‐O) and MeS(O)‐O‐CH2‐C(R1)=C=CR2R3 (4) respectively. An attractive application of the method is the easy preparation of the natural compound myrcene from 4 in which R1, R2 and R3 are hydrogen. A mechanistic rational for the reactions is discussed.