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Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization.
Angew Chem Int Ed Engl. 2020 12 07; 59(50):22706-22713.AC

Abstract

We report chiral RhIII cyclopentadienyl-catalyzed enantioselective synthesis of lactams and isochromenes through oxidative [4+1] and [5+1] annulation, respectively, between arenes and 1,3-enynes. The reaction proceeds through a C-H activation, alkenyl-to-allyl rearrangement, and a nucleophilic cyclization cascade. The mechanisms of the [4+1] annulations were elucidated by a combination of experimental and computational methods. DFT studies indicated that, following the C-H activation and alkyne insertion, a RhIII alkenyl intermediate undergoes δ-hydrogen elimination of the allylic C-H via a six-membered ring transition state to produce a RhIII enallene hydride intermediate. Subsequent hydride insertion and allyl rearrangement affords several rhodium(III) allyl intermediates, and a rare RhIII η4 ene-allyl species with π-agostic interaction undergoes SN2 '-type external attack by the nitrogen nucleophile, instead of C-N reductive elimination, as the stereodetermining step.

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Authors+Show Affiliations

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China.

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China.

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China.

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China.

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China.

School of Chemistry and Chemical Engineering, Shaanxi Normal University (SNNU), Xi'an, 710062, China. Institute of Molecular Science and Engineering, Institute of Frontier and Interdisciplinary Sciences, Shandong University, Qingdao, 266237, China.

Pub Type(s)

Journal Article

Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

32886841

Citation

Sun, Jiaqiong, et al. "Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: a Distinct Mechanism of Allyl Formation and Allyl Functionalization." Angewandte Chemie (International Ed. in English), vol. 59, no. 50, 2020, pp. 22706-22713.

Sun J, Yuan W, Tian R, et al. Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization. Angew Chem Int Ed Engl. 2020;59(50):22706-22713.

Sun, J., Yuan, W., Tian, R., Wang, P., Zhang, X. P., & Li, X. (2020). Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization. Angewandte Chemie (International Ed. in English), 59(50), 22706-22713. https://doi.org/10.1002/anie.202010832

Sun J, et al. Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: a Distinct Mechanism of Allyl Formation and Allyl Functionalization. Angew Chem Int Ed Engl. 2020 12 7;59(50):22706-22713. PubMed PMID: 32886841.

* Article titles in AMA citation format should be in sentence-case

TY - JOUR T1 - Rhodium(III)-Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3-Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization. AU - Sun,Jiaqiong, AU - Yuan,Weiliang, AU - Tian,Rong, AU - Wang,Peiyuan, AU - Zhang,Xue-Peng, AU - Li,Xingwei, Y1 - 2020/10/07/ PY - 2020/08/07/received PY - 2020/9/5/pubmed PY - 2020/9/5/medline PY - 2020/9/4/entrez KW - C−H activation KW - asymmetric catalysis KW - enynes KW - lactams KW - rhodium SP - 22706 EP - 22713 JF - Angewandte Chemie (International ed. in English) JO - Angew Chem Int Ed Engl VL - 59 IS - 50 N2 - We report chiral RhIII cyclopentadienyl-catalyzed enantioselective synthesis of lactams and isochromenes through oxidative [4+1] and [5+1] annulation, respectively, between arenes and 1,3-enynes. The reaction proceeds through a C-H activation, alkenyl-to-allyl rearrangement, and a nucleophilic cyclization cascade. The mechanisms of the [4+1] annulations were elucidated by a combination of experimental and computational methods. DFT studies indicated that, following the C-H activation and alkyne insertion, a RhIII alkenyl intermediate undergoes δ-hydrogen elimination of the allylic C-H via a six-membered ring transition state to produce a RhIII enallene hydride intermediate. Subsequent hydride insertion and allyl rearrangement affords several rhodium(III) allyl intermediates, and a rare RhIII η4 ene-allyl species with π-agostic interaction undergoes SN2 '-type external attack by the nitrogen nucleophile, instead of C-N reductive elimination, as the stereodetermining step. SN - 1521-3773 UR - https://www.unboundmedicine.com/medline/citation/32886841/Rhodium_III__Catalyzed_Asymmetric_[4+1]_and_[5+1]_Annulation_of_Arenes_and_13_Enynes:_A_Distinct_Mechanism_of_Allyl_Formation_and_Allyl_Functionalization_ DB - PRIME DP - Unbound Medicine ER -