More Like this

1. Intramolecular cycloaddition/rearrangement cascade from gold( iii )-catalysed reactions of propargyl aryldiazoesters with cinnamyl imines

   https://doi.org/10.1039/C8CC07885H  

   Qiu, Huang; Arman, Hadi; Hu, Wenhao; Doyle, Michael P. (November 2018, Chemical Communications)

   Conjugated cycloheptene-1,4-dione-enamines are cycloaddition products from a surprising rearrangement in a Au( iii )-catalysed reaction between propargyl aryldiazoacetates and cinnamyl imines. This complex transformation occurs through an initial rapid Au( iii )-catalysed [4+3]-cycloaddition to form dihydroazepinyl aryldiazoacetates followed by a subsequent uncatalyzed domino transformation that occurs by sequential [3+2]-cycloaddition-/nitrogen extrusion and acyloxy migration/retro-Michael addition/tautomerization. 

   more » « less
2. Photoinduced [4 + 2]-cycloaddition reactions of vinyldiazo compounds for the construction of heterocyclic and bicyclic rings

   https://doi.org/10.1039/D4SC03558E  

   Bao, Ming; Bohórquez, Arnold_R Romero; Arman, Hadi; Doyle, Michael P (January 2024, Chemical Science)

   Highly selective formal [4 + 2]-cycloaddition of vinyldiazoacetates with azoalkenes from a-halohydrazones, as well as with cyclopentadiene and furan, occurs with light irradiation at room temperature, producing highly functionalized heterocyclic and bicyclic compounds in good yields and excellent diastereoseletivity. Under blue light these vinyldiazoacetate reagents selectively form unstable cyclopropenes that undergo intermolecular cycloaddition reactions at a faster rate than their competitive ene dimerization. [4 + 2]-cycloaddition of vinyldiazoacetates with in situ formed azoalkenes produces bicyclo[4.1.0]tetrahydropyridazine derivatives and, together with their cycloaddition using cyclopentadiene and furan that form tricyclic compounds, they occur with high chemoselectivity and diastereocontrol, good functional group tolerance, and excellent scalability. Subsequent transformations portray the synthetic versatility of these structures. 

   more » « less
3. Functionalized vinyldiazo compounds: New players in asymmetric catalysis

   https://doi.org/10.1016/j.checat.2023.100770  

   Bao, M; De_Angeles, L; Rada, MS; Baird, M; Arman, H; Wherritt, D; Doyle, MP (October 2023, Chem Catalysis)

   The catalytic uses of metal carbenes for addition, insertion, and cycloaddition reactions are dependent on their carbene precursor. The limited methods available for the preparation of diazo esters, which are the most common carbene precursors, restricts their ability to impart structural diversity in metal carbene reactions. Here we report a new methodology for the preparation of diverse vinyldiazoacetate esters and their effective uses in highly enantiocontrolled cyclopropanation, N-H bond insertion, O-H bond insertion, and [3+2] cycloaddition reactions. 1,2,3-Triazine 1-oxides with a sp3-C-H bond at the 5-position undergo base catalyzed Dimroth-type rearrangement to form multiply substituted oximidovinyldiazoacetates in high yields at or below room temperature, and these diverse vinyldiazo compounds undergo catalytic metal carbene transformations to produce oximidovinylcyclopropanes, α-oximidovinyl-α-amino acids and α-hydroxy acids, as well as tricyclic indole derivatives in high yields and enantioselectivities. The new access to vinyldiazo compounds has applicability to a vast array of metal carbene transformations. 

   more » « less
4. HNTf ₂ -Catalyzed Formal [3 + 2] Cycloaddition of Vinyldiazoacetates to Indole-Substituted Diazo Compounds and Their Conversion to Carbazoles

   https://doi.org/10.1021/acs.orglett.4c01628  

   Bao, Ming; Carriola, Diana_Victoria Navarrete; Arman, Hadi; Doyle, Michael P (June 2024, Organic Letters)

   Triflimide catalysis of the [3 + 2]-cycloaddition of 3-indolymethanols with vinyldiazoacetates provides general access to β-tetrahydrocyclopenta[b]indol-substituted α-diazoesters. Initiated by addition of the in situ generated vinylogous iminium electrophile from 3-indolymethanol to the vinylogous position of the vinyldiazo compound and completed by intramolecular cyclization from the vinyldiazonium ion intermediate, this transformation occurs in good yields and excellent diastereoselectivity with a broad substrate scope under mild conditions. The resulting α-diazoesters undergo Rh2(OAc)4-catalyzed substrate-dependent 1,2-migration to form multisubstituted carbazoles in high yields. 

   more » « less
5. Challenges in the Highly Selective [3 + 1]-Cycloaddition of an Enoldiazoacetamide to Form a Donor–Acceptor Cis-Cyclobutenecarboxamide

   https://doi.org/10.3390/molecules26123520  

   Joyasawal, Sipak; Ma, Donghui; Doyle, Michael P. (June 2021, Molecules)

   A substituted donor–acceptor cyclobutenecarboxamide is synthesized with modest enantiocontrol through a chiral copper(I) complex catalyzed [3 + 1]-cycloaddition reaction of α-acyl diphenylsulfur ylides with 3-siloxy-2-diazo-3-butenamides. With a methyl substituent on the 4-position of the 3-butenamide, the cis-vicinal-3,4-disubstituted cyclobutenecarboxamide is formed with >20:1 diastereocontrol. Donor-acceptor 3-methyl-2-siloxycyclopropenecarboxamide is rapidly formed from the reactant enoldiazoamide and undergoes catalytic ring opening to give only the Z-γ-substituted metallo-enolcarbene. Elimination from 3-siloxy-2-diazo-3-pentenamide to form the conjugated 3-siloxy-2,4-pentadienamide is competitive but minimized at low temperature. 

   more » « less