Cross-metathesis with Vinyl Derivatives

The functionalization of SAMs via ruthenium-catalyzed cross metathesis of vinyl-terminated SAMs has been reported by Lee et al.76 to install a variety of acrylic derivatives on SAMs bearing vinyl groups on their outer surface. The major drawback of this approach is the intra-SAM metathesis which causes the formation of a mixture of surface-bound products, limiting the reproducibility of the method. The formation of urethanes by the reaction of diisocyanates77 or isothiocyanates78 with hydroxyl- and amino-terminated SAMs has been reported as well. The reaction of hydroxyl-terminated SAMs with diisocyanates, allowed the preparation of isocyanate SAMs that proved to be reactive towards amines, alcohols, and water, displaying the standard chemistry of the isocyanate groups.77... 

Cross-metathesis of trialkoxy- and trisiloxy-substituted vinylsilanes [21] as well as octavinylsilsesquioxane [15] with vinyl sulfides proceeds efficiently but only in the presence of the 2nd generation Grubbs catalysts (IV) to offer a new and very attractive route for syntheses of [alkyl(aiyl)]sulfide-substituted vinylsilanes and vinyl-silsesquioxane with high preference for the -isomer, as illustrated by exclusive isolation of such isomers. The Fischer-type ruthenium carbene complex Ru(=CHSPh)Cl2(PCy3)2 has recently been reported as an effective catalyst in the ring opening/cross-metathesis of norbomene derivatives with vinyl sulfide [22], suggesting that these carbenes can be reactive in the cross-metathesis. 

CROSS-METATHESIS OF VINYL-SUBSTITUTED ORGANOSILICON DERIVATIVES WITH OLEFINS AND DIENES IN THE PRESENCE OF GRUBBS CATALYSTS... 

Silylative Coupling and Cross-Metathesis of Alkenes and Dienes with Vinyl-Silicon Derivatives — New Catalytic Routes to Synthesis of OrganosUicon Compounds ... 

On the other hand, although well-defined or in-situ initiated metallacarbenes are inactive for selfmetathesis of vinyl-substituted silanes and siloxanes, we revealed recently a high catalytic activity of Grubbs catalyst in cross-metathesis of vinyltrialkoxysilanes and vinyltrisiloxanes with styrene, 1-alkenes and selected allyl ethers and other derivatives [10-12]. 

Lesma and associates began their synthesis of (-b)-monomorine I (1562) with the N-Boc -protected amine 1623, a simple derivative of (5)-pyroglu-tamic acid (Scheme 205). Reaction with allyltrimethylsilane in the presence of boron trifluoride according to a reported procedure and replacement of the Boc group by Cbz produced the 2,5-n s-disubstituted pyrrolidine (—)-1624, cross-metathesis of which with methyl vinyl ketone... 

Chloromethyl polystyrene can be converted to a free-radical initiator by reaction with 2,2,6,6-tetramethylpipcridinc-/V-oxyl (TEMPO). Radical polymerization of various substituted alkenes on this resin has been used to prepare new types of polystyrene-based supports [123]. Alternatively, cross-linked vinyl polystyrene can be copolymerized with functionalized norbornene derivatives by ruthenium-mediated ringopening metathesis polymerization [124],... 

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