TY - JOUR
T1 - Small Molecule Activation with Intramolecular “Inverse” Frustrated Lewis Pairs
AU - Manankandayalage, Chamila
AU - Unruh, Daniel K.
AU - Krempner, Clemens
N1 - Funding Information:
This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Science Program, under Award DE-SC0019094. The authors would like to thank Shipra Garg for providing us with a sample of 9-Ph-BBN.
Funding Information:
This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Science Program, under Award DE‐SC0019094. The authors would like to thank Shipra Garg for providing us with a sample of 9‐Ph‐BBN.
Publisher Copyright:
© 2021 Wiley-VCH GmbH
PY - 2021/4/7
Y1 - 2021/4/7
N2 - The intramolecular “inverse” frustrated Lewis pairs (FLPs) of general formula 1-BR2-2-[(Me2N)2C=N]-C6H4 (3–6) [BR2=BMes2 (3), BC12H8, (4), BBN (5), BBNO (6)] were synthesized and structurally characterized by multinuclear NMR spectroscopy and X-ray analysis. These novel types of pre-organized FLPs, featuring strongly basic guanidino units rigidly linked to weakly Lewis acidic boryl moieties via an ortho-phenylene linker, are capable of activating H−H, C−H, N−H, O−H, Si−H, B−H and C=O bonds. 4 and 5 deprotonated terminal alkynes and acetylene to form the zwitterionic borates 1-(RC≡C-BR2)-2-[(Me2N)2C=NH]-C6H4 (R=Ph, H) and reacted with ammonia, BnNH2 and pyrrolidine, to generate the FLP adducts 1-(R2HN→BR2)-2-[(Me2N)2C=NH]-C6H4, where the N-H functionality is activated by intramolecular H-bond interactions. In addition, 5 was found to rapidly add across the double bond of H2CO, PhCHO and PhNCO to form cyclic zwitterionic guanidinium borates in excellent yields. Likewise, 5 is capable of cleaving H2, HBPin and PhSiH3 to form various amino boranes. Collectively, the results demonstrate that these new types of intramolecular FLPs featuring weakly Lewis acidic boryl and strongly basic guanidino moieties are as potent as conventional intramolecular FLPs with strongly Lewis acidic units in activating small molecules.
AB - The intramolecular “inverse” frustrated Lewis pairs (FLPs) of general formula 1-BR2-2-[(Me2N)2C=N]-C6H4 (3–6) [BR2=BMes2 (3), BC12H8, (4), BBN (5), BBNO (6)] were synthesized and structurally characterized by multinuclear NMR spectroscopy and X-ray analysis. These novel types of pre-organized FLPs, featuring strongly basic guanidino units rigidly linked to weakly Lewis acidic boryl moieties via an ortho-phenylene linker, are capable of activating H−H, C−H, N−H, O−H, Si−H, B−H and C=O bonds. 4 and 5 deprotonated terminal alkynes and acetylene to form the zwitterionic borates 1-(RC≡C-BR2)-2-[(Me2N)2C=NH]-C6H4 (R=Ph, H) and reacted with ammonia, BnNH2 and pyrrolidine, to generate the FLP adducts 1-(R2HN→BR2)-2-[(Me2N)2C=NH]-C6H4, where the N-H functionality is activated by intramolecular H-bond interactions. In addition, 5 was found to rapidly add across the double bond of H2CO, PhCHO and PhNCO to form cyclic zwitterionic guanidinium borates in excellent yields. Likewise, 5 is capable of cleaving H2, HBPin and PhSiH3 to form various amino boranes. Collectively, the results demonstrate that these new types of intramolecular FLPs featuring weakly Lewis acidic boryl and strongly basic guanidino moieties are as potent as conventional intramolecular FLPs with strongly Lewis acidic units in activating small molecules.
KW - C−H bond activation
KW - N−H bond activation
KW - borane
KW - frustrated Lewis pair
KW - hydrogen cleavage
UR - http://www.scopus.com/inward/record.url?scp=85102205234&partnerID=8YFLogxK
U2 - 10.1002/chem.202005143
DO - 10.1002/chem.202005143
M3 - Article
C2 - 33567143
SN - 0947-6539
VL - 27
SP - 6263
EP - 6273
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 20
ER -