α,α′-C–H Bond Difunctionalization of Unprotected Alicyclic Amines
作者:Daniel A. Valles、Subhradeep Dutta、Anirudra Paul、Khalil A. Abboud、Ion Ghiviriga、Daniel Seidel
DOI:10.1021/acs.orglett.1c02187
日期:2021.8.20
A simple one-pot procedure enables the sequential, regioselective, and diastereoselective introduction of the same or two different substituents to the α- and α′-positions of unprotected azacycles. Aryl, alkyl, and alkenyl substituents are introduced via their corresponding organolithium compounds. The scope of this transformation includes pyrrolidines, piperidines, azepanes, and piperazines.
Diversification of Unprotected Alicyclic Amines by C−H Bond Functionalization: Decarboxylative Alkylation of Transient Imines
作者:Anirudra Paul、Jae Hyun Kim、Scott D. Daniel、Daniel Seidel
DOI:10.1002/anie.202011641
日期:2021.1.18
efforts by many practitioners in the field, methods for the direct α‐C−H bond functionalization of unprotected alicyclic amines remain rare. A new advance in this area utilizes N‐lithiated alicyclic amines. These readily accessible intermediates are converted to transient imines through the action of a simple ketone oxidant, followed by alkylation with a β‐ketoacid under mild conditions to provide valuable
A Selenourea-Thiourea Brønsted Acid Catalyst Facilitates Asymmetric Conjugate Additions of Amines to α,β-Unsaturated Esters
作者:Yingfu Lin、William J. Hirschi、Anuj Kunadia、Anirudra Paul、Ion Ghiviriga、Khalil A. Abboud、Rachael W. Karugu、Mathew J. Vetticatt、Jennifer S. Hirschi、Daniel Seidel
DOI:10.1021/jacs.9b12457
日期:2020.3.25
enantioselectivity via the conjugate addition of cyclic amines to unactivated α,β-unsaturated esters. A related strategy enables the kineticresolution of racemic cyclic 2-arylamines, using benzyl acrylate as the resolving agent. Reactions are facilitated by an unprecedented selenourea-thiourea organocatalyst. As elucidated by DFT calculations and 13C kinetic isotope effects studies, the rate-limiting and enantiodetermining
Borane-Catalyzed Transfer Hydrogenations of Pyridines with Ammonia Borane
作者:Qiwen Zhou、Lanqiong Zhang、Wei Meng、Xiangqing Feng、Jing Yang、Haifeng Du
DOI:10.1021/acs.orglett.6b02610
日期:2016.10.21
With the use of ammoniaborane as a hydrogen source, a borane catalyzed metal-free transferhydrogenation of pyridines was successfully realized for the first time to furnish a variety of piperidines in 44–88% yields with moderate to excellent cis-selectivities. The ease in handling without requiring high pressure H2 makes this transferhydrogenation practical and useful.
Unprotected cis-2,3-diarylpiperidines are synthesized from readily available piperidines in only three operations. The key step is a palladium-catalyzed cross-coupling reaction between aryl halides and endocyclic 1-azallyl anions, elusive intermediates derived from the in situ deprotonation of 2-aryl-1-piperideines. This cross-coupling reaction can be achieved enantioselectively with a chiral mono-phosphine