Cross‐Coupling with Organosilicon Compounds

Abstract

Organosilicon functions possess many properties that make them ideal donors of organic groups in cross‐coupling reactions. Through the addition of an appropriate silicophilic Lewis base, an in situ pentacoordinate silane can effectively transfer an organic group. This feature allows for the rapid development of silicon cross‐coupling methods that continue today. Organosilicon‐based cross‐coupling has now become a practical, viable, and in some cases, superior compared with organoboron,‐zinc,‐tin couplings. The unique properties of organosilicon compounds provide a number of distinct advantages to their use as donors in transition‐metal catalyzed cross‐coupling reactions: 1, silicon moieties can be introduced into organic substrates by many general and high‐yielding methods for the construction of silicon carbon bonds; 2, organosilicon reagents are chemically robust and allow isolation and purification of products and are compatible with many functional groups; 3, silicon‐containing by‐products of the coupling are of low molecular weight, are nontoxic, and are easily removed from the reaction mixture; 4, a number of mild methods are available. This chapter presents a thorough overview of the various combinations of transferable groups and organic electrophiles. The scope is limited to the combination of silicon‐bearing nucleophiles with halo or related electrophiles under catalysis by palladium or nickel complexes wherein the silyl halide is lost.

The hexadehydro-Diels–Alder reaction

“…2b) vs. entry 1]; ii] the activating carbonyl group can be a distal (carboalkoxy) rather than a tethering substituent (entries 2 and 3); iii] many classical methods of aryne generation are not compatible with electron-withdrawing groups in the substrate; 20 iv] carbonyl activation is not a necessity (entries 1, 4, and 7); v] products having nitrogen-containing heterocycles annulated to the new arene ring can be prepared (entries 3–5); vi] an ester tether (entry 6) cyclizes more slowly than its N -phenyl amide analog (entry 5), consistent with the lower concentration of the s -cis conformation required for ring closure; vii] our observations are consistent with the absence of radical character in both the cycloaddition and trapping phases of the process; e.g., reactions performed in chloroform solvent, an excellent hydrogen atom donor, have shown no evidence of hydrogen atom transfer (entries 4 and 9); viii] the new silyl ether trapping reaction has considerable generality (entries 1–3, 5, 6, and 8 and Fig. 2); ix] other efficient internal benzyne traps include tethered alcohols (entries 4 and 7), aryl rings ([4+2] cycloaddition in entry 9), or alkenes (ene reaction in entry 10); x] seven-membered ring formation is feasible (entry 8), and the robust nature of the substrate and product at the high temperature required for this slower cyclization are noteworthy; and xi] the silyl substituents in many of the products provide handles for subsequent elaboration through protonative, oxidative, or halogenative desilylation or cross-coupling reactions 21 .…”

Regioselective Allene Hydrosilylation Catalyzed by N-Heterocyclic Carbene Complexes of Nickel and Palladium

“…1 For example, the Hiyama cross-coupling 2 and Sakurai-type allylation and crotylation reactions 3 are widely used methods for C-C bond formation. Currently, the most direct and atom-economical routes to vinyl- and allylsilanes proceed via metal-catalyzed hydrosilylations of π-components (Scheme 1).…”

Why You Really Should Consider Using Palladium-Catalyzed Cross-Coupling of Silanols and Silanolates

“…Fortunately, recent comprehensive reviews of the area provide a thorough treatment of the advantages of each activating group and the transformations for which it is suitable together with the reaction conditions needed to effect the cross-coupling. 69,70 …”