Intermolecular exo-selective Diels–Alder reaction catalysed by dual-functional Brønsted acid: conformational restriction of transition states by hydrogen bonds as the key interaction DOI Creative Commons

Taishi Nakanishi,

Masahiro Terada

RSC Advances, Год журнала: 2023, Номер 13(51), С. 36293 - 36300

Опубликована: Янв. 1, 2023

An exo-selective Diels-Alder (exo-DA) reaction in which the formed diastereomer is different from that conventional endo-selective (endo-DA) was developed, involves a dual-functional Brønsted acid as catalyst and not only dienophile (vinylquinoline) but also an acyclic diene (dienylcarbamate) having sterically less demanding substituent. Factors necessary for achieving exo-DA were extracted through exhaustive computational search of corresponding transition states, relative orientation firmly defined by hydrogen bonding interactions with catalyst. It experimentally verified combined use catalyst, such phosphoric acid, conformationally restricted (dienylcarbamate), realized introduction substituent at 2-position unit, key to reaction. A catalytic enantioselective attempted using chiral gave rise exo-adduct fairly good enantioselectivity.

Язык: Английский

Organocatalytic Asymmetric Synthesis of 2,3-Dihydro-4H-imidazol-4-ones via Cyclocondensation of N-Silyl Iminoesters DOI

K. Ogura,

Shota Ando,

Tsunayoshi Takehara

и другие.

ACS Catalysis, Год журнала: 2024, Номер 14(18), С. 13792 - 13799

Опубликована: Сен. 2, 2024

Chiral 2,3-dihydro-4H-imidazol-4-ones are key motifs in both synthetic and biological chemistry. However, their accessibility is classically limited to optical resolution of enantioenriched products. Herein, we report the catalytic asymmetric synthesis these 4-imidazolones via cyclocondensation N-silyl iminoesters N-unprotected ketimines using a chiral phosphoric acid catalyst. The enantioselective reaction has broad substrate tolerance maintains high yields enantioselectivities (up 99%, 99% ee). Furthermore, dimerization afford various imidazolones was performed same system 95%, obtained products were easily converted into significant heterocyclic molecules such as imidazoles, imidazolidines, nitrones. Experimental results density functional theory (DFT) calculations revealed plausible mechanism origin induction.

Язык: Английский

Процитировано

1

Divergent asymmetric reactions of α-alkenyl ketones with β,γ-alkynyl-α-imino esters enabled by chiral phosphoric acids DOI Creative Commons
Guosong Shen,

Faqian He,

Xiaoyu Yang

и другие.

Green Synthesis and Catalysis, Год журнала: 2024, Номер unknown

Опубликована: Окт. 1, 2024

Язык: Английский

Процитировано

1

KHMDS/Triglyme Cryptate as an Alternative to Phosphazene Base in Stereodivergent Pentafluoroethylation of N-Sulfinylimines Using HFC-125 DOI
Yuji Sumii, Hiroto Iwasaki,

Yamato Fujihira

и другие.

The Journal of Organic Chemistry, Год журнала: 2022, Номер 87(23), С. 15806 - 15819

Опубликована: Окт. 31, 2022

A protocol for the stereodivergent pentafluoroethylation of N-sulfinylimines using HFC-125 with KHMDS/triglyme has been developed. Both diastereomers pentafluoroethylated amines can be selectively synthesized based on presence or absence triglyme. This additive-controlled allows cryptate to a straightforward and cheap alternative previously reported base-controlled trifluoromethylation potassium hexamethyldisilazide (KHMDS) versus P4-tBu.

Язык: Английский

Процитировано

6

Enantioselective Friedel–Crafts Reaction of Heteroaromatic Compounds with Glyoxals Catalyzed by Chiral Oxazaborolidinium Ion Catalyst DOI

Shinyeong Han,

Injoo Seo,

Do Hyun Ryu

и другие.

Organic Letters, Год журнала: 2023, Номер 25(37), С. 6813 - 6817

Опубликована: Сен. 13, 2023

A catalytic enantioselective Friedel-Crafts reaction of various heteroaromatic compounds with glyoxals has been developed. In the presence a chiral oxazaborolidinium ion catalyst, provided α-hydroxyketones in high yield (up to 96%) excellent enantioselectivity >99% ee). The synthetic utility this method was illustrated by conversion products derivatives such as 1,2-diol and β-amino alcohol.

Язык: Английский

Процитировано

1

Five-membered ring systems: pyrroles and benzo analogs DOI
Justin M. Lopchuk

Progress in heterocyclic chemistry, Год журнала: 2023, Номер unknown, С. 199 - 250

Опубликована: Янв. 1, 2023

Язык: Английский

Процитировано

1

Intermolecular exo-selective Diels–Alder reaction catalysed by dual-functional Brønsted acid: conformational restriction of transition states by hydrogen bonds as the key interaction DOI Creative Commons

Taishi Nakanishi,

Masahiro Terada

RSC Advances, Год журнала: 2023, Номер 13(51), С. 36293 - 36300

Опубликована: Янв. 1, 2023

An exo-selective Diels-Alder (exo-DA) reaction in which the formed diastereomer is different from that conventional endo-selective (endo-DA) was developed, involves a dual-functional Brønsted acid as catalyst and not only dienophile (vinylquinoline) but also an acyclic diene (dienylcarbamate) having sterically less demanding substituent. Factors necessary for achieving exo-DA were extracted through exhaustive computational search of corresponding transition states, relative orientation firmly defined by hydrogen bonding interactions with catalyst. It experimentally verified combined use catalyst, such phosphoric acid, conformationally restricted (dienylcarbamate), realized introduction substituent at 2-position unit, key to reaction. A catalytic enantioselective attempted using chiral gave rise exo-adduct fairly good enantioselectivity.

Язык: Английский

Процитировано

0