Visible‐Llight Driven Organophotocatalyzed Multicomponent Reaction for C(sp3)–H Alkylation of Phosphoramides with in situ Generated Michael Acceptors

Author(s):  
Krishna Gopal Ghosh ◽  
Debabrata Das ◽  
Palasetty Chandu ◽  
Devarajulu Sureshkumar
Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 97
Author(s):  
Shamsunnahar Khushi ◽  
Angela A. Salim ◽  
Ahmed H. Elbanna ◽  
Laizuman Nahar ◽  
Robert J. Capon

Thorectandra choanoides (CMB-01889) was prioritized as a source of promising new chemistry from a library of 960 southern Australian marine sponge extracts, using a global natural products social (GNPS) molecular networking approach. The sponge was collected at a depth of 45 m. Chemical fractionation followed by detailed spectroscopic analysis led to the discovery of a new tryptophan-derived alkaloid, thorectandrin A (1), with the GNPS cluster revealing a halo of related alkaloids 1a–1n. In considering biosynthetic origins, we propose that Thorectandrachoanoides (CMB-01889) produces four well-known alkaloids, 6-bromo-1′,8-dihydroaplysinopsin (2), 6-bromoaplysinopsin (3), aplysinopsin (4), and 1′,8-dihydroaplysinopsin (10), all of which are susceptible to processing by a putative indoleamine 2,3-dioxygenase-like (IDO) enzyme to 1a–1n. Where the 1′,8-dihydroalkaloids 2 and 10 are fully transformed to stable ring-opened thorectandrins 1 and 1a–1b, and 1h–1j, respectively, the conjugated precursors 3 and 4 are transformed to highly reactive Michael acceptors that during extraction and handling undergo complete transformation to artifacts 1c–1g, and 1k–1n, respectively. Knowledge of the susceptibility of aplysinopsins as substrates for IDOs, and the relative reactivity of Michael acceptor transformation products, informs our understanding of the pharmaceutical potential of this vintage marine pharmacophore. For example, the cancer tissue specificity of IDOs could be exploited for an immunotherapeutic response, with aplysinopsins transforming in situ to Michael acceptor thorectandrins, which covalently bind and inhibit the enzyme.


2019 ◽  
Vol 43 (22) ◽  
pp. 8644-8650 ◽  
Author(s):  
Mohit Saroha ◽  
Jitender M. Khurana

Acetic acid mediated regioselective synthesis of novel 2,4,5-trisubstituted thiazole derivatives has been reported by a domino reaction of thiosemicarbazide and aldehydes/ketones/isatin, to generate thiosemicarbazones (in situ) followed by addition of arylglyoxal and active methylene/activated C–H acids/pyrazole/indole in ethanol at 80 °C.


2008 ◽  
Vol 61 (6) ◽  
pp. 419 ◽  
Author(s):  
Matthew J. Spafford ◽  
James E. Christensen ◽  
Matthew G. Huddle ◽  
Joshua R. Lacey ◽  
Ram S. Mohan

A bismuth trifluoromethanesulfonate (triflate)-catalyzed (2.0 mol-%) multicomponent reaction involving the allylation of dioxolanes followed by in situ derivatization with anhydrides to generate highly functionalized esters has been developed under solvent-free conditions. Most reagents used to date for allylation of dioxolanes are highly corrosive and are often required in stoichiometric amounts. In contrast, the use of a relatively non-toxic and non-corrosive bismuth(iii)-based catalyst makes this methodology especially attractive for scale-up.


2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Zubi Sadiq ◽  
Erum Akbar Hussain ◽  
Narjis Naz ◽  
Ambreen Ghani ◽  
Kausar Yasmeen ◽  
...  

A new series of tetrahydrocarbazole coupled 1,2-diazoles 4/5/6(a–o) in moderate to excellent yield was synthesized successfully via multicomponent reaction approach by adopting Michael type-addition of hydrazines on in situ generated α,β-unsaturated ketones via aldol type strategy under synthetic microwave radiations and conventional heating. Structural confirmations of all the prepared compounds were achieved by spectroscopic techniques. The best results were achieved when equal amounts of water-acetic acid were used in microwave conditions in 4 minutes.


2019 ◽  
Vol 4 (13) ◽  
pp. 3717-3721 ◽  
Author(s):  
Vediyappan Ramesh ◽  
Natarajan Savitha Devi ◽  
Marappan Velusamy ◽  
Sivakumar Shanmugam

Author(s):  
Douglass Taber

Mohammad Navid Soltani Rad of Shiraz University of Technology has shown (Tetrahedron Lett. 2007, 48, 6779) that with tosylimidazole (TsIm) activation in the presence of NaCN, primary, secondary and tertiary alcohols are converted into the corresponding nitriles. Gregory C. Fu of MIT has devised (J. Am. Chem. Soc. 2007, 129, 9602) a Ni catalyst that mediated the coupling of sp3-hybridized halides such as 3 with sp3-hybridized organoboranes such as 4, to give 5. Usually, carbanions with good leaving groups in the beta position do not couple efficiently, but just eliminate. Scott D. Rychnovsky of the University of California, Irvine has found (Organic Lett . 2007, 9, 4757) that initial protection of 6 as the alkoxide allowed smooth reduction of the sulfide and addition of the derived alkyl lithium to the amide 7 to give 8. Doubly-activated Michael acceptors such as 11 are often too unstable to isolate. J. S. Yadav of the Indian Institute of Chemical Technology, Hyderabad has shown (Tetrahedron Lett. 2007, 48, 7546) that Baylis-Hillman adducts such as 9 can be oxidized in situ, with concomitant Sakurai addition to give 12. Rather than use the usual Li or Na or K enolate, Don M. Coltart of Duke University has found (Organic Lett. 2007, 9, 4139) that ketones such as 13 will condense with amides such as 14 to give the diketone 15 on exposure to MgBr2. OEt2 and i -Pr2 NEt. Simultaneously, Gérard Cahiez of the Université de Cergy (Organic Lett. 2007, 9, 3253) and Janine Cossy of ESPCI Paris (Angew. Chem. Int. Ed. 2007, 46, 6521) reported that Fe salts will catalyze the coupling of sp2 -hybridized Grignard reagents such as 17 with alkyl halides. John Montgomery of the University of Michigan has described (J. Am. Chem. Soc. 2007, 129, 9568) the Ni-mediated regio- and enantioselective addition of an alkynes 20 to an aldehyde 19 to give the allylic alcohol 21. In a third example of sp2 - sp3 coupling, Troels Skrydstrup of the University of Aarhus has established (J. Org. Chem. 2007, 72, 6464) that Negishi coupling with alkenyl phosponates such as 23 proceeded efficiently.


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