Stereospecific synthesis of (1E,3Z)- and (1E,3E)-1-trimethylsilyl-1,3- dienes by means of sequential cross-coupling reactions

A Novel Stereoselective Synthesis of Symmetrical (1E,3E)-1,4-Diarylbuta-1,3-dienes

“…The homocoupling of alkenylstannanes, 11 vinylboronic acids 12 or unsaturated silanes, 13 as well as the metal-promoted reductive dimerization of vinyl halides 14 have been used as synthetic tools for the synthesis of symmetrically functionalized buta-1,3-dienes. A number of methodologies for the prep-aration of unsymmetrically functionalized buta-1,3dienes have also been developed based on cross-coupling reactions of vinyl halides or triflates with alkenyl-substituted organometallic compounds such as vinylboron, 15 -tin, 16 -zinc, 17 -germanium, 18 -zirconium, 19 or -magnesium 20 derivatives. In many cases these homocoupling and cross-coupling processes are highly stereoselective.…”

Highly Stereoselective Synthesis of Conjugated Polyenes via a Homocoupling Reaction of Unsaturated Silanes

“…GLC/mass spectrometry analyses were performed on a fused silica capillary column SE 30, 30 m. Melting points are uncorrected. (1 E ,3 E )-1,4-Bis(trimethylsilyl)-1,3-butadiene ( 1a ), (1 E ,3 E ,5 E )-1,6-bis(trimethylsilyl)-1,3,5-hexatriene ( 1b ), (1 E ,3 E ,5 E ,7 E )-1,8-bis(trimethylsilyl)-1,3,5,7-octatetraene ( 1c ), (2 E ,4 E )-1-phenyl-5-(trimethylsilyl)-2,4-pentadien-1-one ( 2a ),20a (2 E ,4 E ,6 E )-1-phenyl-7-(trimethylsilyl)-2,4,6-heptatrien-1-one ( 2b ),20a (3 E ,5 E ,7 E )-1-phenyl-8-(trimethylsilyl)-3,5,7-octatrien-2-one ( 2c ),20c and (1 E ,3 E )-1-phenyl-4-(trimethylsilyl)-1,3-butadiene ( 2g ) were prepared as reported in the literature. Copper(II) bromide and copper(II) chloride were commercial products, dried at 150 °C (0.1 mbar) for 2 h, and stored in a nitrogen atmosphere.…”

Linchpin dienes: key building-blocks in the synthesis of polyenic frameworks

“…Both (E,E)-9.2 and (E,Z)-9.2 isomers were prepared from alkenyl bromide possessing the appropriate configuration of the double bond (Scheme 43). 63,64 These bifunctionalized dienes proved to be sufficiently reactive to be coupled under Ni(II)-catalyzed conditions with a Grignard reagent in good yields and with total retention of the configuration of the double bonds. However, when the (Z,E)-9.2 reagent was used, the choice of the catalyst was crucial and satisfactory results were obtained with NiCl 2 (dppm) 2 .…”