474267-11-3Relevant academic research and scientific papers
Synthetic and Mechanistic Investigation of an Oxime Ether Electrocyclization Approach to Heteroaromatic Boronic Acid Derivatives
Mora-Radó, Helena,Sotorríos, Lia,Ball-Jones, Matthew P.,Bialy, Laurent,Czechtizky, Werngard,Méndez, María,Gómez-Bengoa, Enrique,Harrity, Joseph P. A.
, p. 9530 - 9534 (2018/07/14)
A range of functionalized heteroaromatic boronic acid derivatives are readily accessed by a diboration/6π-electrocyclization sequence. This study revealed the surprising observation that there is a direct relationship between oxime ether stereochemistry and reactivity towards electrocyclization. Specifically, E-oxime ethers are found to be significantly more reactive than their Z-counterparts (stereochemistry relative to azatriene scaffold). In contrast, the configuration at the azatriene alkene terminus has little impact on reaction rates. Computational analysis offers a rationale for this observation; a Nlone pair→C=C π* orbital interaction lowers the energy of the transition state in the electrocyclization of E-oxime ethers. Finally, unreactive Z-oxime ethers can be converted to the corresponding heterocyclic products by a photolytically promoted E→Z isomerization and electrocyclization sequence.
Synthesis of β- and γ-carbolines by the palladium/copper-catalyzed coupling and cyclization of terminal acetylenes
Zhang, Haiming,Larock, Richard C.
, p. 7048 - 7056 (2007/10/03)
A variety of 3-substituted β- and γ-carbolines have been synthesized from N-substituted 3-iodoindole-2-carboxaldehydes and 2-bromoindole-3-carboxaldehydes, respectively. The coupling of these aldehydes with various terminal acetylenes with PdCl2(PPh3)2/CuI as the catalyst readily affords the corresponding alkynylindole carboxaldehydes, which have subsequently been converted to the corresponding tert-butylimines and cyclized to β- and γ-carbolines by either copper-catalyzed or thermal processes.
