Synthesis 2023; 55(08): 1227-1240
DOI: 10.1055/a-2001-6888
paper

Indication of Pd–C or Cu–C Intermediates in Bimetallic Nanoclusters During Pd/Au-PVP- or Cu/Au-PVP-Catalyzed Oxidations of endo-4-Oxatricyclo[5.2.1.02,6]-8-decene and Tetrahydro-γ-carbolines

Shunya Morita
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Zhaoyang Ren
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Lingaraju Gorla
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Zongbo Tong
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Edruce Edouarzin
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Boris Averkiev
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
,
Victor W. Day
b   Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA
,
Duy H. Hua
a   Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
› Author Affiliations
We are grateful to the National Institutes of Health, the National Institute of General Medical Sciences (R01 GM128659) and the National Science Foundation (CHE-1662705) for financial support of this research. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This material was based upon work in part supported by the National Science Foundation under grant no. 1826982 (to D.H.H.) for the purchase of a NMR spectrometer and grant CHE-2018414 (to D.H.H.) for the purchase of an X-ray diffractometer.


Abstract

Catalytic oxidation of tricyclic endo-norbornene-fused tetrahydrofuran with the bimetallic nanocluster Cu/Au-PVP in the presence of H2O2 or t-BuOOH as the oxidant leads to C–H bond oxidation adjacent to the ether function to give 4-oxa-tricyclo[5.2.1.0]-8,9-exo-epoxydecane, however, oxidation with Pd/Au-PVP takes place at the C=C double bond to give the same epoxide and the oxidative three-bond forming dimeric product, dodecahydro-1,4:6,9-dimethanodibenzofurano[2,3-b:7,8-b′]bisoxolane. Formation of the latter product suggests the involvement of a reactive Pd–C intermediate. Similarly, oxidative C–C bond-forming reactions are observed in cycloaddition reactions of N2-Boc-1,2,3,4-tetrahydro-γ-carbolines and 2,3-dihydroxybenzoic acid with Cu/Au-PVP (2–5 mol%) and H2O2 at 25 °C, providing two-bond-forming [4+2] cycloadducts. Under similar reaction conditions, Pd/Au-PVP did not produce the corresponding cycloadduct, indicating a need for complexation between Cu and the carboxylic acid group of 2,3-dihydroxybenzoic acid and the allylic amine function of the γ-carbolines during the cyclization reaction. The reported intermolecular coupling reactions using Pd/Au-PVP or Cu/Au-PVP nanocluster catalysts under oxidative conditions at 25 °C are unprecedented.

Supporting Information



Publication History

Received: 18 November 2022

Accepted after revision: 20 December 2022

Accepted Manuscript online:
20 December 2022

Article published online:
19 January 2023

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