Abstract
A new class of chiral bicyclic [1,2,3]-triazolooxazine derived N-heterocyclic carbene (NHC) ligands was synthesised in its enantiopure form from commercially available, cheap amino acid without undertaking any chiral resolution. In particular, the bicyclic N-heterocyclic carbene precursor, (S)-7-benzyl-6,6-(R1)2–2-R2-[1,2,3]-triazolooxazinium iodide [R1 = R2 = Me (1a); R1 = H, R2 = Me (2a); R1 = H, R2 = Et (3a)] salts were conveniently prepared by the N-alkylation reactions of the corresponding [1,2,3]- triazolooxazine derivatives with alkyl iodides in ca. 37–73% yields. The copper mediated [3 + 2] cycloaddition reaction of the PhCH2CH(N3)CR2OH (R = H, Me) azido alcohol compounds and propargyl bromide gave the desired [1,2,3]-triazolooxazines. These chiral bicyclic [1,2,3]- triazolooxazine derived N-heterocyclic carbene ligands were characterised in the form of its silver (NHC)AgCl (1–3)b, gold (NHC)AuCl (1–3)c, and the palladium (NHC)2PdCl2 (1–3)d and the PEPPSI type (NHC)PdI2(NC5H5) (1–3)e complexes (NHC = (S)-7-benzyl-6,6-(R1)2–2-R2-[1,2,3]-triazolooxazin-3-ylidene; R1 = H, Me and R2 = Me, Et; PEPPSI = Pyridine Enhanced Precatalyst Preparation Stabilisation and Initiation).
Original language | English |
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Article number | 115011 |
Number of pages | 17 |
Journal | Polyhedron |
Volume | 197 |
DOIs | |
Publication status | Published - 15 Mar 2021 |
Externally published | Yes |
Bibliographical note
Funding Information:We thank the Department of Science and Technology (Grant No: SR/S1/IC-50/2011, EMR/2014/000254, CRG/2019/000029) New Delhi, India, for financial support of this research. We gratefully acknowledge the Single Crystal X-ray Diffraction Facility, Department of Chemistry, IIT Bombay, Mumbai, India, for the crystallographic characterization data. M.K.G, A.P.P thank CSIR, New Delhi, India, and S.R.D thanks IIT Bombay, Mumbai, India for research fellowships.
Funding
We thank the Department of Science and Technology (Grant No: SR/S1/IC-50/2011, EMR/2014/000254, CRG/2019/000029) New Delhi, India, for financial support of this research. We gratefully acknowledge the Single Crystal X-ray Diffraction Facility, Department of Chemistry, IIT Bombay, Mumbai, India, for the crystallographic characterization data. M.K.G, A.P.P thank CSIR, New Delhi, India, and S.R.D thanks IIT Bombay, Mumbai, India for research fellowships.
Keywords
- Asymmetric Michael
- Bicyclic triazolooxazine derived ligands
- Chiral N-heterocyclic carbene (NHC)
- Gold complexes
- Homogeneous catalysis
- Palladium complexes
- Silver complexes
- Transmetallation reactions