Ethyl group

Summary

In organic chemistry, an ethyl group (abbr. Et) is an alkyl substituent with the formula , derived from ethane (). Ethyl is used in the International Union of Pure and Applied Chemistry's nomenclature of organic chemistry for a saturated two-carbon moiety in a molecule, while the prefix "eth-" is used to indicate the presence of two carbon atoms in the molecule. Ethylation Ethylation is the formation of a compound by introduction of the ethyl group. The most widely practiced example of this reaction is the ethylation of benzene with ethylene to yield ethylbenzene, a precursor to styrene, which is a precursor to polystyrene. Approximately 24.7 million tons of ethylbenzene were produced in 1999. :: Many ethyl-containing compounds are generated by electrophilic ethylation, i.e. treatment of nucleophiles with sources of Et+. Triethyloxonium tetrafluoroborate [Et3O]BF4 is such a reagent. For good nucleophiles, less electrophilic reagents are employed, such as ethyl halides

Official source

https://en.wikipedia.org/wiki/Ethyl_group

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The thesis deals with the development of transition metal-catalyzed difunctionalization of alkenes and alkynes, which can be categorized into two major topics: (1) palladium-catalyzed diamination of alkynes for the synthesis of tetracycles; (2) copper-catalyzed cyanoalkylation-initiated double functionalization of alkenes. The first part of this thesis describes the synthesis of free NH tetracyclic indoles by palladium-catalyzed diamination of triple bonds. In the presence of palladium catalyst, 1,2-diarylethynes bearing an N-methyl-N-[2-(methoxy-carbonyl)ethyl]amino and an aminocarbonyl/aminosulfonyl group at the ortho positions of the two aromatic rings underwent double cyclization in a highly ordered fashion to afford N-2-(methoxycarbonyl)ethylaed indolo[3,2-c]isoquinolinone or indolobenzothiazine S,S-dioxide with complete chemoselectivity. Subsequently, the N-[2-(methoxycarbonyl)ethyl] group is readily removed under basic conditions (DBU, DMF, 120 °C) to afford tetracycles with indolyl nitrogen unprotected. We subsequently developed a transition metal-free diamination process to access the tetracyclic quindolinones. In the presence of acetic acid and a hydride donor (Hantsch¿s ester) under oxygen atmosphere, double cyclization of 1,3-diarylprop-2-yn-1-ones bearing an N,N-dialkylated amino and an N-monoalkylated amino groups at ortho positions of aromatic rings occurred smoothly to provide tetracyclic quindolinones. In the second part of thesis, copper-catalyzed cyanoalkylative difunctionalization of alkenes with alkylnitriles as alkylative reagents was addressed. We developed catalytic conditions (copper salt, ligand, peroxide, base) that allowed us to convert unactivated alkenes to 1,2-difunctionalized alkanes or its cyclic variants. The domino process proceeded through following key elementary steps: a) generation of cyanolakyl radicals; b) addition of cyanoalkyl radical to unactivated double bond; c) interception of this adduct radical by a suitable reagent, or more frequently, oxidation of adduct radical to carbenium; d) trapping of the carbocation by an internal/or external nucleophile. By applying this strategy, a series of value-added molecules such as dihydroisobenzofurans, gamma-lactones, aziridines and gamma-azidobutyronitriles, were readily synthesized from simple alkenes.

EPFL2017

Sulfonamide and Tertiary Amine as Nucleophiles in Pd(II)-Catalyzed Diamination of Alkynes: Synthesis of Tetracyclic Indolobenzothiazine S,S‑Dioxides

Minh Tu Ha, Qian Wang, Bo Yao, Jieping Zhu

Pd(II)-catalyzed oxidative double cyclization of the 1,2-diarylethynes bearing an N-methyl-N-(2-methoxycarbonyl)ethylamino and an aminosulfonyl group afforded indolobenzothiazine S,S-dioxides in good to excellent yields. The 2-(methoxycarbonyl)ethyl group attached to the indolyl nitrogen is readily removed under basic conditions (DBU, DMF, 120 °C) to provide the corresponding tetracycles with a free indolyl nitrogen in excellent yields.

American Chemical Society2015

2-(Methoxycarbonyl)ethyl as a Removable N-Protecting Group: Synthesis of Indoloisoquinolinones by Pd(II)-Catalyzed Intramolecular Diamination of Alkynes

Minh Tu Ha, Qian Wang, Bo Yao, Jieping Zhu

Pd(II)-catalyzed double cyclization of 1,2-diarylethynes bearing an N-methyl-N-[2-(methoxycarbonyl)ethyl]amino and an aminocarbonyl group at the ortho positions of the two aromatic rings afforded the tetracyclic N-[2-(methoxycarbonyl)-ethyl]indoloisoquinolinones in good to excellent yields. The N-[2-(methoxycarbonyl)ethyl] group is readily removed under basic conditions (DBU, DMF, 120 °C) to afford the corresponding tetracycles with a free indolyl nitrogen in excellent yields. The 2-(methoxycarbonyl)ethyl as a removable N-protecting group is illustrated in other Pd(II)- and Pd(0)-catalyzed and selenium-mediated transformations.

Amer Chemical Soc2015

EPFL2017