883141-48-8Relevant academic research and scientific papers
Catalyst-Controlled Regioselectivity in Pd-Catalyzed Aerobic Oxidative Arylation of Indoles
Wang, Dian,Salazar, Chase A.,Stahl, Shannon S.
supporting information, p. 2198 - 2203 (2021/05/07)
Pd-catalyzed C-H arylation of heteroarenes is an important and widely studied synthetic transformation; however, the regioselectivity is often substrate-controlled. Here, we report catalyst-controlled regioselectivity in the Pd-catalyzed oxidative coupling ofN-(phenylsulfonyl)indoles and aryl boronic acids using O2as the oxidant. Both C2- and C3-arylated indoles are obtained in good yield with >10:1 selectivity. A switch from C2 to C3 regioselectivity is achieved by adding 4,5-diazafluoren-9-one or 2,2′-bipyrimidine as an ancillary ligand to a “ligand-free” Pd(OTs)2catalyst system. Density functional theory calculations indicate that the switch in selectivity arises from a change in the mechanism, from a C2-selective oxidative-Heck pathway to a C3-selective C-H activation/reductive elimination pathway.
The synthesis of 2- and 3-aryl indoles and 1,3,4,5-tetrahydropyrano[4,3-b]indoles and their antibacterial and antifungal activity
Leboho, Tlabo C.,Michael, Joseph P.,van Otterlo, Willem A.L.,van Vuuren, Sandy F.,de Koning, Charles B.
scheme or table, p. 4948 - 4951 (2009/12/24)
A series of 2- and 3-aryl substituted indoles and two 1,3,4,5-tetrahydropyrano[4,3-b]indoles were synthesized from indole and 5-methoxyindole. The 2-aryl indoles were synthesized from the 1-(phenylsulfonyl)indole derivatives using magnesiation followed by iodination. The 2-iodinated compounds were then subjected to Suzuki-Miyaura reactions. In addition, the 3-aryl indoles were made from the corresponding 3-bromoindoles using Suzuki-Miyaura reactions. The 1,3,4,5-tetrahydropyrano[4,3-b]indoles were also synthesized from 1-(phenylsulfonyl)indole by magnesiation followed by treatment with allylbromide. The product was then converted into [2-allyl-1-(phenylsulfonyl)-1H-indol-3-yl]methanol which upon exposure to Hg(OAc)2 and NaBH4 afforded tetrahydropyrano[4,3-b]indoles. A number of the 2- and 3-aryl indoles displayed noteworthy antimicrobial activity, with compound 13a displaying the most significant activity (3.9 μg/mL) against the Gram-positive micro-organism Bacillus cereus.
A concise synthesis of novel naphtho[a]carbazoles and benzo[c]carbazoles
Pathak, Rakhi,Nhlapo, Johanna M.,Govender, Sameshnee,Michael, Joseph P.,Van Otterlo, Willem A. L.,De Koning, Charles B.
, p. 2820 - 2830 (2007/10/03)
Starting from simple indole precursors the synthesis of naphtho[a]carbazoles and benzo[c]carbazoles is described. Key steps include the use of the Suzuki-Miyaura reaction to afford 2- or 3-aryl substituted indoles, as well as a potassium t-butoxide and light assisted aromatic ring-forming reaction.
