Intermolecular cross-coupling

In 1991, Inanaga achieved Sml2-mediated intermolecular cross-coupling between C=0 (ketones or aldehydes) and C=N by using 0-benzyl formaldoxime as a C=N component7 The reaction requires HMPA as a co-solvent and a suitable proton source such as /-butyl alcohol or ethylene glycol. A cross-coupling reaction between ketones and... 

Intermolecular Cross-Coupling Reactions Followed by Intermolecular Cycloadditions... 

Scheme 30 Preparation of ring-annelated arenes [108] and cyclohexadienes [110] by intra-intermolecular cross couplings with subsequent 6jr-electrocyclizations...

Scheme 31 Intra-intermolecular cross-coupling-6jr-electrocyclization sequences incorporating bicyclopropylidene (37) [111]...

The classical Ullmann reaction has also attracted renewed interest in recent years. Miyano has prepared optically enriched binaphthyl derivatives by intramolecular biaryl coupling, as shown in equation (9). " Diastereoselectivities of up to 70% have been obtained with a binaphthol chiral auxiliary in the linking chain. Intermolecular cross-coupling is best accomplished with preformed arylcopper compounds. "... 

Scheme 30 Lu s intermolecular cross-coupling of simple arenes by double C-H activation...

Li R, Jiang L, Lu W (2006) Intermolecular cross-coupling of simple arenes via C-H activation by tuning concentrations of arenes and TFA. Organometallics 25 5973-5975... 

An intermolecular cross-coupling requires that the simple alkyne be a better binder to Ru than the propargylic alcohol. co-Cyanoalkynes meet that requirement. Thus, 6-cyano-l-hexyne generates the crossed coupled produd in 75% yield (Equation 1.28) [25]. 

A single attempt has been made to induce asymmetry in the intermolecular cross coupling reaction by employing a chiral ligand for the samarium ketyl [56]. Utilizing 2,2 -bis(diphenylphosphinyl)-l,l -binaphthyl (BINAPO) as a chiral ligand, a modest start has been made to develop an enantioselective process. However, in the examples reported to date the method is plagued by low yields and/or moderate stereoselectivities. 

In recent years, heterogeneous copper-catalyzed intermolecular cross-coupling has been successfully applied for the synthesis of a variety of heterocyclic compounds. 

The polymerization sequence of B-R-9-BBN prepared from 1,7-octadiene is employed [6] for intermolecular cross-coupling with 1,4-dibromobenzene or 1,4-diiodobenzene in the presence of dichloro[l,l -bis(diphenylphosphino) ferrocene] palladium (II) [PdCl2(dppf)j. Similarly, hydroboration of diolefin with 9-BBN, followed by the intermolecular cross-coupling of the resulting a,co-bis(B-alkanediyl-9-BBN) with dihaloarenes are performed in the presence of PdCl2(dppf), a base, and phase-transfer catalyst [7]. Both the steps are performed in the same flask. 

Palladium-catalyzed hydroboration, haloboration, and similar reactions involving addition of organoboron compounds to alkynes have been reviewed.Alkylborane addition to alkynes followed by intra- or intermolecular cross-coupling with a vinyl halide or triflates according to the Suzuki-Miyaura protocol constitutes a very powerful synthetic route for the generation of two carbon-carbon bonds in cascade. This subject and its applications in synthesis have been reviewed. ... 

Pt(PPh3)4 reacts with iodobenzene derivatives having OGH2SnBu3 or OGH2SiMe3 substituents at the 2-position to form the 3-oxa-platinacycle 399 (Scheme 55). Oxidative addition of a G-I bond to Pt(0) is followed by intramolecular transmetallation via activation of the G-Sn or G-Si bonds. The reactions proceed smoothly without additives, although intermolecular cross-coupling of aryl triflate with vinyl(tributyl)stannane promoted by the Pt complex requires addition of a base such as K2GO3. 

A facile synthesis of y-ketophosphonates (589) has been realised by intermolecular cross-coupling reaction of aromatic aldehydes (587) with vinylphosphonates (588), catalysed by N-heterocyclic carbine (589) in moderate to good yields (Scheme 171). ... 

Recently a Ni-catalyzed reductive cyclization/intermolecular cross-coupling has been reported by Peng et al. [190] for the synthesis of aryl-substituted spiroacetals (Scheme 93). 

The coupling reaction of zirconocene alkyne complexes with a second alkyne provides a general method for the preparation of asymmetrically substituted zircona-cyclopentadienes. The overall transformation is the chemoselective and regioselec-tive intermolecular cross-coupling reaction of two alkynes (Scheme 12.33) [44]. 

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