Organotrifluoroborates

With this rule in mind the outcome of CM-reactions can often be predicted. In the synthesis of organotrifluoroborate 79 [143] the terminal double bond is a type 1 substrate, while the 1,1-disubstituted olefin can be considered type III. The reaction of 2-methyl-1,4-pentadiene 77 with type II cross-partner 78 furnishes 79 efficiently (only 2 mol% catalyst used) in good yields after two steps. 

Figure 3.42. Scope of Rh/(if)-binap-catalyzed asymmetric 1,4-addition of potassium organotrifluoroborates to methyl iV-acetamidoacrylate in the presence of guaiacol.

Molander GA, Ellis N (2007) Organotrifluoroborates protected boronic acids that expand the versatility of the Suzuki coupling reaction. Acc Chem Res 40 275-286... 

Scheme 9. Proposed mechanism for the Suzuki cross-coupling reaction of arene diazonium salts with potassium organotrifluoroborates based on ESl-MS investigation, m/z vaiues are given for cationic intermediates observed by ESl(+)-MS.

The reaction of aliphatic alcohols and potassium organotrifluoroborate salts also gives ethers. ... 

Tremblay-Morin, J.-P., Raeppel, S., Gaudette, F. Lewis acid-catalyzed Mannich type reactions with potassium organotrifluoroborates. Tetrahedron Lett. 2004, 45, 3471-3474. 

Molander, G. A., Dehmel, F. Formal Total Synthesis of Oximidine II via a Suzuki-Type Cross-Coupling Macrocyclization Employing Potassium Organotrifluoroborates. J. Am. Chem. Soc. 2004, 126, 10313-10318. 

Quach, T. D., Batey, R. A. CopperfllFCatalyzed Ether Synthesis from Aliphatic Alcohols and Potassium Organotrifluoroborate Salts. Org. Lett. 2003, 5,1381-1384. 

Unsaturated organotrifluoroborate salts are cleaved at the CC multiple bond to yield carbonyl compounds. The trifluoroborate group is resistant to attack by ozone. ... 

Organotrifluoroborates in organic synthesis (reactions with oxiranes, epox-idation of, hetaryltrifluoroborates in Suzuki reaction) 05AA49. 

Yoshida and coauthors have reported a facile preparation of iodonium salts 367 by the reaction of potassium organotrifluoroborates 366 with (difluoroiodo)arenes under mild conditions (Scheme 2.104) [396]. A similar approach to alkynyliodonium salts by the reaction of alkynyldifluoroboranes with polyfluoroorganyliodine difluorides was developed by Frohn and Bardin [501]. 

Phenylboronic acid (17) and its derivatives are widely used. Boronic acids are sometimes difficult to purify because they undergo cyclotrimerizadon with loss of water to form boroxines. On the other hand, organotrifluoroborate salts 18 are easily prepared, purified, and handled [23]. Aryltrifluoroborate salts 18 are prepared by the reaction of arylboronic acid with HF and base [24]. Alkenyltrifluorobo-rates 19 are prepared by hydroboration of 1-alkynes, followed by treatment with KHF2 [25]. 

These potassium organotrifluoroborates are good partners of S-MC [26]. Coupling of PI1BF3K (20) with deactivated / -bromoanisole proceeds with ligandless Pd catalyst in refluxing MeOH in the presence of K2CO3 [27]. Reaction of more... 

Scheme 3.25 Asymmetric 50b-catalyzed conjugate addition of organotrifluoroborate...

Scheme 4.5). Potassium organotrifluoroborate salts are easily accessible, have attracted increased commercial availability, are air- and moisture-stable alternatives to boronic acids as well as their esters, and can be stored for long periods of time without decomposition under ambient reaction conditions. These aryl donors function brilhantly in arylations of phenols, albeit with the requirement for 2 equiv. of the potassium organotrifluoroborate salt being used to gain the best yields. However, the reactions function even at ambient temperature with molecular oxygen as a co-oxidant [20]. 

A rhodium(l) chloride with chiral diene ligands catalyses addition of potassium organotrifluoroborates (K+ ArBFg") to A-sulfanyl ketimines, effecting C-arylation in good to excellent yields, and ee s up to 99.5%. 0... 

---