23092-23-1Relevant academic research and scientific papers
Gold-catalyzed [4+3]-Annulations of Benzopyriliums with Vinyldiazo Carbonyls to Form Bicyclic Heptatriene Rings with Skeletal Rearrangement
Sekar Kulandai Raj, Antony,Liu, Rai-Shung
, p. 2517 - 2522 (2020)
We report gold catalyzed [4+3]-annulations between benzopyriliums and 3-alkyl-2-diazo-3-vinyl carbonyls, yielding 7H-benzo[7]annulene products efficiently. Notably, the carbon skeletons of resulting 7H-benzo[7]annulenes are structurally rearranged, accompanied by migrations of their alkyl and ketone motifs. Apart from applicable substrates over a wide scope, these annulatios are applicable to pyriliums and 3-alkyl-2-diazo-3-vinyl esters to increase their reaction significance. We postulate a mechanism involving an initial [4+2]-cycloaddition between benzopyriliums and 3-alkyl-2-diazo-3-vinyl carbonyl species, followed by formation of gold carbenes to induce a ring expansion and group migrations. (Figure presented.).
Triplet sensitized photolysis of a vinyl azide: Direct detection of a triplet vinyl azide and nitrene
Rajam, Sridhar,Jadhav, Abhijit V.,Li, Qian,Sarkar, Sujan K.,Singh, Pradeep N. D.,Rohr, Ahleah,Pace, Tamara C. S.,Li, Rui,Krause, Jeanette A.,Bohne, Cornelia,Ault, Bruce S.,Gudmundsdottir, Anna D.
, p. 9325 - 9334 (2014)
Photolysis of vinylazide 1, which has a built-in acetophenone triplet sensitizer, in argon-saturated toluene results in azirine 2, whereas irradiation in oxygen-saturated toluene yields cyanide derivatives 3 and 4. Laser flash photolysis of azide 1 in argon-saturated acetonitrile shows formation of vinylnitrene 1c, which has a max at ～300 nm and a lifetime of ～1 ms. Vinylnitrene 1c is formed with a rate constant of 4.25 × 105 s-1 from triplet 1,2-biradical 1b. Laser flash photolysis of 1 in oxygen-saturated acetonitrile results in 1c-O (max = 430 nm, τ ≈ 420 μs acetonitrile). Density functional theory (DFT) calculations were used to aid in the characterization of the intermediates formed upon irradiation of azide 1 and to validate the proposed mechanism for its photoreactivity.
Direct formation and reactions of allylic thienyl-based organocopper reagents
Klein,Rieke
, p. 2635 - 2644 (1992)
The lithium naphthalenide reduction of lithium 2-thienylcyanocuprate produces a highly reactive zero-valent copper complex. This allows for the direct formation of allylic organocopper reagents and ensuing cross-couplings with electrophiles.
The application of bis(oxazoline) ligands in the catalytic enantioselective methallylation of aldehydes
Hargaden, Grainne C.,McManus, Helen A.,Cozzi, Pier Giorgio,Guiry, Patrick J.
, p. 763 - 766 (2007)
The application of symmetric and non-symmetric bis(oxazoline) ligands in the asymmetric methallylation of a range of aromatic and aliphatic aldehydes was investigated. Catalytic asymmetric methallylation of benzaldehyde was performed, using acetonitrile l
Bis(oxazolinyl)phenylrhodium(III) Aqua Complex: Efficiency in Enantioselective Addition of Methallyltributyltin to Aldehydes under Aerobic Conditions
Motoyama, Yukihiro,Nishiyama, Hisao
, p. 1883 - 1885 (2003)
A simple and general protocol is described for the enantioselective addition of methallyltributyltin to aldehydes catalyzed by chiral (Phebox)RhCl2(H2O) complexes 1 [Phebox = 2,6-bis(oxazolinyl)phenyl]. The reaction can be performed
Gold-Catalyzed Bicyclic Annulations of 2-Alkynylbenzaldehydes with Vinyldiazo Carbonyls that Serve as Five-atom Building Units
Raj, Antony Sekar Kulandai,Liu, Rai-Shung
, p. 10980 - 10984 (2019)
This work reports gold-catalyzed bicyclic annulations of 2-alkynyl-1-carbonylbenzenes with vinyldiazo ketones that serve as five-atom building units. The importance of these reactions is to access 4,5-dihydro-benzo[g]indazoles, which form the structural cores of various bioactive molecules. According to our mechanistic analysis, we postulate initial [5+4]-cycloadditions between benzopyrilium intermediates and vinyldiazo ketones, followed by 6-π-electrocyclizations to achieve the excellent stereoselectivity.
Bidirectional asymmetric allylboration and the synthesis of C2 symmetric 3-methylenepentane-1,5-diols
Barrett, Anthony G. M.,Braddock, D. Christopher,De Koning, Pieter D.
, p. 459 - 460 (1999)
The double allylboration of aldehydes using 1,3-bis(diisopinocampheylboryl)-2-methylenepropane under Brown's salt-free conditions provides C2 symmetric 3-methylenepentane-1,5-diols in excellent enantiomeric excess.
Diastereoselective construction of cis 2,6-disubstituted tetrahydropyran rings via In(OTf)3-catalyzed intramolecular 2,5-oxonium-ene cyclization: Synthetic studies towards the total synthesis of zampanolide and dactylolide
Loh, Teck-Peng,Yang, Jian-Ying,Feng, Li-Chun,Zhou, Yan
, p. 7193 - 7196 (2002)
Diastereoselective construction of 2,6-disubstituted tetrahydropyrans with an exocyclic double bond was achieved via the In(OTf)3-catalyzed intramolecular 2,5-oxonium-ene cyclization. Its application was further demonstrated by the synthesis of
Ring Expansion Fluorination of Unactivated Cyclopropanes Mediated by a New Monofluoroiodane(III) Reagent
Chen, Ze,Du, Feng-Huan,Hu, Ze-Nan,Jia, Meng-Cheng,Ren, Jing,Zhang, Chi
supporting information, p. 24171 - 24178 (2021/10/08)
Herein, we report a new strategy for carbon?carbon bond scission and intramolecular ring expansion fluorination of unactivated cyclopropanes, which was accomplished with a new hypervalent fluoroiodane(III) reagent 1. This novel method delivers medicinally relevant 4-fully substituted fluoropiperidines in moderate to high yields with excellent regio- and diastereoselectivity. Reagent 1, which has an N-acetylbenziodazole framework, was readily synthesized via three steps in 76 % overall yield and was characterized by NMR spectroscopy and X-ray crystallography. Owing to the presence of a secondary I???O bonding interaction between the λ3-iodane atom and the carbonyl oxygen of the acetyl group of the N-acetylbenziodazole framework, 1 has excellent stability and can be stored at ambient temperature for 6 months without any detectable decomposition. Density functional theory calculations and experimental studies showed that the reaction proceeds via a carbocation intermediate that readily combines with a fluoride ion to generate the product.
Accessing novel fluorinated heterocycles with the hypervalent fluoroiodane reagent by solution and mechanochemical synthesis
Browne, Duncan L.,Jones, Andrew C.,Riley, William,Singh, Kuldip,Stuart, Alison M.
supporting information, p. 7406 - 7409 (2021/08/03)
A new and efficient strategy for the rapid formation of novel fluorinated tetrahydropyridazines and dihydrooxazines has been developed by fluorocyclisation of β,γ-unsaturated hydrazones and oximes with the fluoroiodane reagent. Mechanochemical synthesis d
