Pd - Catalyzed Synthsis Of Conjugate Dienes From Alkynols And Alkenes

Alkenes represent one of the most widely occurring and important classes of organic compounds. Just for the synthesis of acyclic monoalkenes, there are close to ten different, basic structural types, so how to develop efficient, selective, and practical synthesis methods for them has become a major challenge to synthetic organic chemists.Iterative hydroboration protonolysis of unsymmetrically disubstituted 1, 3-butadiynes producing (Z, Z)-1, 3-butadienes in 1970 by Zweifel is one of the earliest examples of fully selective syntheses of stereo- and regiodefined conjugated dienes. Based on this work, Negishi group discovered fully selective methods for the syntheses of the (E, Z) - and (E, E) - isomers in 1973. These methods were soon supplanted by the Pd-catalyzed alkenyl alkenyl coupling with alkenyl metals containing Al, Zr, and Zn discovered and developed by Negishi group during the 1976-1978 period. The uncatalyzed alkenylboron route to (E, Z)-1, 3-dienes via (E)-1, 3-enynes was developed in 1979 by the group of A. Suzuki. Although not widely used, even today, this must still be considered as one of the most efficient and selective routes to 1, 4-disubstituted (E, Z)-butadienes. Nevertheless, the efficient and selective Pd-catalyzed alkenyl alkenyl coupling is by far the most generally applicable and predictably satisfactory method for the synthesis of 1, 4-disubstituted 1, 3-dienes.Recently, some new methods of selective syntheses of stereo- and regiodefined conjugated dienes were developed. For example: phosphine-mediated olefination between aldehydes and allenes; highly selective nickel-catalyzed three-component coupling of alkynes with enones and alkenyl boronic acids, etc.In this paper, we present a Pd-catalyzed high regio- and stereoselective synthsis of conjugate dienes from alkynols and alkenes.The notable advantages of this method are that we have described a new facile and efficient method for the synthesis of high substituted 1, 3-dienes via Pd-catalyzed intermolecular reaction from alkynols and alkenes. The high regio- and stereoselectivity and tolerance for a range of functional groups as well as the mild reaction conditions made the present protocol very attractiveness.