Synthesis of new asymmetric substituted boron amidines - reactions with CO and transfer hydrogenations of phenylacetyleneElectronic supplementary information (ESI) available: Spectroscopic and crystallographic details. CCDC 1051038 for 2b, 1051039 for 2a and 1051040 for 3a. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt01966d

• Main Authors: Cabrera, Alan R, Rojas, Rene S, Valderrama, Mauricio, Plüss, Pascal, Berke, Heinz, Daniliuc, Constantin G, Kehr, Gerald, Erker, Gerhard
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt01966d

The syntheses of the new asymmetric substituted boron amidines [ N ′-(2,6-diisopropylphenyl)- N -(pentafluorophenyl)acetimidamide]bis(pentafluorophenyl)borate ( 2a ) and [ N ′-(2,6-diisopropylphenyl)- N -(4-cyanophenyl)acetimidamide]bis(pentafluorophenyl)borate ( 2b ) were achieved by reaction of one equivalent of HB(C 6 F 5 ) 2 and the respective amidines 1a and 1b . These adducts, bearing electron withdrawing groups, showed thermally induced H 2 elimination forming the four-membered cyclic diazaborate derivatives 3a and 3b . These new species were characterized by spectroscopic methods. X-ray diffraction studies have been carried out on 2a , 2b and 3a . To prevent undesired reactions at the nitrile group, one equivalent of B(C 6 F 5 ) 3 was added to 2b yielding the 2b -B(C 6 F 5 ) 3 nitrile adduct 4 . Compound 4 underwent thermally induced dehydrogenation to give the four-membered cyclic diazaborate derivative 5 . CO was inserted into the ring systems of 2a and 2b forming the five-membered diazaborolone derivatives 6a and 6b . Phenylacetylene reacted stoichiometrically with the asymmetric substituted boron amidines 2a , 2b and 4 to give styrene by double H transfer. Formation of amidine-BH(C 6 F 5 ) 2 adducts and their thermal dehydrogenation, CO uptake to form five-membered cyclic compounds and stoichiometric transfer hydrogenation toward phenylacetylene.