Metal-Free Photoinduced Hydrocyclization of Unactivated Alkenes toward Ring-Fused Quinazolin-4(3H)-ones via Intermolecular Hydrogen Atom Transfer

Abstract

A visible-light-induced hydrocyclization of unactivated alkenes was developed using 3CzClIPN as the photocatalyst to generate substituted α-methyldeoxyvasicinones and α-methylmackinazolinones in moderate to good yields. An intermolecular hydrogen atom transfer with THF as the hydrogen source was involved. Mechanism studies indicated that the intramolecular addition of the in situ formed aminal radical to the unactivated alkene generated the polycyclic quinazolinone.

Catalyst-free photoinduced radical sulfonylation/cyclization of unactivated alkenes toward sulfone-containing quinazolinones

“…Based on the above results and previous reports, 57–59 a plausible reaction mechanism is shown in Fig. 4.…”

“…The prominence of quinazolinones for bioactivity studies in medicinal chemistry led us to choose them as the receptor for this Minisci reaction, but at the same time their weakly active CvN double bond made the implementation of this design more challenging. [54][55][56][57][58][59] Herein, we present a catalyst-free photoinduction system that initiates free radical sulfonylation and cyclization reactions of unactivated olefins to conveniently and efficiently produce a wide range of sulfonated quinazolinones.…”

Cyclizations of Alkenyl(Alkynyl)‐Functionalized Quinazolinones and their Heteroanalogues: A Powerful Strategy for the Construction of Polyheterocyclic Structures

“…of A straightforward photochemical access to α-methyldeoxyvasicinones and α-methylmackinazolinones 95 has recently been reported which involves the visible-light-induced hydrocyclization of 3-alkenylquinazolinones 94 using 2,4,6tri(9H-carbazol-9-yl)-5-chloroisophthalonitrile (3CzClIPN) as a photocatalyst (Scheme 30). [118] The key step of the conversion is the generation of aminal radical A, as a result of protonation of 94 and its subsequent SET-reduction by 3CzClIPN. Then the intramolecular addition of the radical…”

Metal-Free Photoredox Intramolecular Cyclization of N-Aryl Acrylamides

“…On the other hand, as one of the most attractive topics in organic chemistry, hydroarylation process has drawn interest of chemists in the past decades [18][19][20][21][22][23][24]. Recently, Pan and our group [25,26] independently reported a visible-light-induced hydrocyclization of unactivated alkenes which generated the polycyclic quinazolinones. (Figure 2a).…”