A number of studies were conducted to demonstrate C-H activation for the construction of C-B bonds. Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable. The reaction at a primary C-H bond of methane or a higher alkene B 2(OR)4 formed an alkylboronate ester R' -B(OR)2 and the accompanying borane H-B(OR2. The ester and the borane were formed on the basis of calculated bond energies for methylboronates and dioaborolanes. The rates of key steps along the reaction pathway for the conversion of a C-H bond in an alkane or arene to the C-B bond in an alkyl or arylboronate ester were favorable. These studies also highlighted the accessible barriers for C-H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.

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C−H Activation for the Construction of C−B Bonds

Cross-coupling reactions of organoboranes: an easy way to construct C-C bonds (Nobel Lecture).

Suzuki–Miyaura (SM) cross-coupling is arguably the most widely-applied transition metal catalysed carbon–carbon bond forming reaction to date. Its success originates from a combination of exceptionally mild and functional group tolerant reaction conditions, with a relatively stable, readily prepared and generally environmentally benign organoboron reagent. A variety of such reagents have been developed for the process, with properties that have been tailored for application under specific SM coupling conditions. This review analyses the seven main classes of boron reagent that have been developed. The general physical and chemical properties of each class of reagent are evaluated with special emphasis on the currently understood mechanisms of transmetalation. The methods to prepare each reagent are outlined, followed by example applications in SM coupling.

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Selection of boron reagents for Suzuki-Miyaura coupling

2.1.8. Michael Reaction 2245 2.1.9. Others 2247 2.2. Cyclization Reactions 2248 2.2.1. Carbon Diels−Alder Reactions 2248 2.2.2. Aza-Diels−Alder Reactions 2252 2.2.3. Other Hetero-Diels−Alder Reactions 2255 2.2.4. Ionic Diels−Alder Reaction 2256 2.2.5. 1,3-Dipolar Cycloadditions 2256 2.2.6. Other Cycloaddition Reactions 2258 2.2.7. Prins-type Cyclization 2259 2.3. Friedel−Crafts Acylation and Alkylation 2259 2.4. Baylis−Hillman Reaction 2263 2.5. Radical Addition 2264 2.6. Heterocycle Synthesis 2267 2.7. Diazocarbonyl Insertion 2270 3. C−X (X ) N, O, P, Etc.) Bond Formation 2271 3.1. Aromatic Nitration and Sulfonylation 2271 3.2. Michael Reaction 2272 3.3. Glycosylation 2273 3.4. Aziridination 2275 3.5. Diazocarbonyl Insertion 2276 3.6. Ring-Opening Reactions 2277 3.7. Other C−X Bond Formations 2280 4. Oxidation and Reduction 2280 4.1. Oxidation 2280 4.2. Reduction 2281 5. Rearrangement 2283 6. Protection and Deprotection 2285 6.1. Protection 2285 6.2. Deprotection 2288 7. Polymerization 2291 8. Miscellaneous Reactions 2291 9. Lanthanide(II) Triflates in Organic Synthesis 2295 10. Conclusion 2295 11. Acknowledgment 2295 12. References 2295

Rare-earth metal triflates in organic synthesis

The Synthesis of Vicinal Amino Alcohols

The palladium-catalyzed cross-coupling reaction of potassium alkynyltrifluoroborates with aryl halides or triflates proceeds readily with moderate to excellent yields. The potassium alkynyltrifluoroborates are air- and moisture-stable crystalline solids that can be stored indefinitely, which will provide an advantage in applications to combinatorial chemistry. The alkynyl cross-coupling reaction can be effected using 9 mol % of PdCl2(dppf)·CH2Cl2 as catalyst in THF or THF−H2O in the presence of Cs2CO3 as the inorganic base. A variety of functional groups are tolerated in both partners.

Development of the suzuki-miyaura cross-coupling reaction: use of air-stable potassium alkynyltrifluoroborates in aryl alkynylations.

Improved reactivity of diiodosamarium by catalysis with transition metal salts

Samarium diiodide/nickel diiodide an efficient system for homo and heterocoupling reactions of imines

Nucleophilic acylation of esters by acid chlorides mediated by samarium diiodide: Formation and use of samarium enediolates

Samarium(II) iodide promotes an efficient one-pot annulation reaction between ω-iodo esters and 2-(ω-chloroalkyl)cycloalkanones. An initial intermolecular carbonyl addition reaction between the iodo ester and the ketone generates a lactone intermediate. The lactone undergoes a subsequent nucleophilic acyl substitution reaction with an organosamarium derived from the chloride. Nickel(II) iodide is an efficient catalyst for the first step of the process, and light is utilized to promote the second step. Seven-, eight-, and nine-membered rings can be accessed by this sequential dianionic process. This annulative approach to carbocycles is complementary to previously reported procedures.

Fouzia Machrouhi

Papers

Development of the suzuki-miyaura cross-coupling reaction: use of air-stable potassium alkynyltrifluoroborates in aryl alkynylations.

Improved reactivity of diiodosamarium by catalysis with transition metal salts

Samarium diiodide/nickel diiodide an efficient system for homo and heterocoupling reactions of imines

Nucleophilic acylation of esters by acid chlorides mediated by samarium diiodide: Formation and use of samarium enediolates

Sequenced reactions with samarium(ii) iodide. a complementary annulation process providing access to seven-, eight-, and nine-membered carbocycles