Palladium(0)‐Catalyzed CarbonHydrogen Bond Functionalization for the Synthesis of Indoloquinazolinones

Abstract

The indoloquinazolinone ring system has attracted considerable attention as a pharmacophore, because it shows various biological activities. The reported synthetic methods for the compound are simple and direct, but are not effective for the direct synthesis of indoloquinazolinone with a methylene group at the C-6 position. A palladium(0)-catalyzed cyclization of chloroquinazolinone via C À H functionalization was developed for a concise synthesis of indoloquinazolinone derivatives. The presence of a substituent at the C-6 position is important for obtaining the product in good yield. The conformation of the reaction intermediate, in particular the N À C À Pd bond angle, is important for the regioselectivity of the reaction.

Palladium(0)-Catalyzed Benzylic C(<i>sp</i>³)–H Functionalization for the Concise Synthesis of Heterocycles and Its Applications

“…36) We also developed a new method for the synthesis of indoloquinazolinones and indoloquinazolinediones based on benzylic C(sp 3 )-H functionalization. 38) In both cases, the presence of an additional ortho substituent was important to the success of the reaction. These results indicate that there is an important steric factor at play resulting from the second ortho substituent, which positively affects the distance between the C(sp …”

“…We also developed a new benzylic C(sp 3 )-H functionalization method for the synthesis of indoloquinazolinones, which represent an important structural class found in several biologically active alkaloids, including tryptanthrin, 96,97) phaitanthirins, 98) and ophiuroidine 38,99) (Fig. 2).…”

“…In this review, we provide a summary of our recent research on the Pd(0)-catalyzed benzylic C(sp 3 )-H functionalization reaction and its application. [33][34][35][36][37][38][39][40][41][42][43] 2. Pd-Catalyzed Benzylic C(sp 3 …”

Palladium-Catalyzed Cascade Approach to 12-(Aryl)indolo[1,2-c]quin­azolin-6(5H)-ones

“…7 As such, the indoloquinazolinone system still motivates organic chemists to develop chemically and economically efficient and sustainable methodologies for their preparation. 8 Although a variety of synthetic methods have been developed for the preparation of natural indoloquinazolinones and their congeners, 3a,9 the synthesis of 12-(aryl)indolo[1,2c]quinazolin-6(5H)-ones 5 is quite challenging.…”

Synthesis of Tetrahydrobiphenylene <i>via</i> Pd(0)-Catalyzed C(<i>sp</i>²)–H Functionalization

“…[21][22][23][24][25][26][27] Recently, we have investigated Pd(0)-catalyzed benzylic C(sp 3 )-H functionalization for the synthesis of various heterocycles and tetrahydro-2H-fluorenes. [28][29][30][31][32][33][34][35][36][37][38][39][40][41] In the synthesis of oxindoles, C(sp 3 )-H activation was favorable over competitive C(sp 2 )-H activation because of the presence of the sp 2 nitrogen linkage 29) (Chart 2a). In contrast, two methyl groups were required for the synthesis of tetrahydro-2H-fluorene through C(sp 3 )-H activation in the presence of the sp 3 carbon linkage (Chart 2b).…”