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An efficient alkoxyl radical-triggered ring expansion/cross-coupling cascade was developed under cheap metal catalysis. Through the metal-catalyzed radical relay strategy, a wide range of medium-sized lactones (9-11 membered) and macrolactones (12, 13, 15, 18, and 19-membered) were constructed in moderate to good yields, along with diverse functional groups including CN, N3, SCN, and X groups installed concurrently. Density functional theory (DFT) calculations revealed that reductive elimination of the cycloalkyl-Cu(iii) species is a more favorable reaction pathway for the cross-coupling step. Based on the results of experiments and DFT, a Cu(i)/Cu(ii)/Cu(iii) catalytic cycle is proposed for this tandem reaction.

Mild and inexpensive copper‐catalyzed aromatization‐driven ring‐opening amination and oxygenation of spiro dihydroquinazolinones are presented, respectively. These protocols provide facile and atom‐economical access to the aminated and the carbonyl‐containing quinazolin‐4(3H)‐ones in good yields with good functional group compatibility, which are difficult to obtain by conventional methods. Remarkably, a telescoped procedure involving the condensation and the ring‐opening/functionalization for simple cycloalkanone was found to be accessible. Mechanistic studies suggest a radical pathway for this transformation. [ABSTRACT FROM AUTHOR]

Metal-free, photoredox-catalyzed aromatization-driven deconstructive functionalization of spiro-dihydroquinazolinones with α-CF3 alkenes is presented. The readily available spiro-dihydroquinazolinones reacted efficiently with α-CF3 alkenes during photocatalysis to give the gem-difluoroallylated and the CF3-containing quinazolin-4(3H)-ones in good yields with excellent chemoselectivity. The selectivity depends on the electron effect of substituents in α-CF3 alkenes. A wide range of four-, five-, six-, seven-, eight- and twelve-membered spiro-dihydroquinazolinones were compatible with this transformation. The protocol is also characterized by the mild and redox-neutral reaction conditions, good functional group compatibility and excellent atom economy. Mechanistic studies revealed that the reaction proceeds via a radical pathway. [ABSTRACT FROM AUTHOR]

A photoredox-catalyzed alkylarylation of activated alkenes via a radical C–C bond cleavage/Truce–Smiles rearrangement cascade is developed. The protocol features mild and redox-neutral conditions, broad substrate scope and excellent functional group compatibility, providing a facile and efficient approach to the long-chain distal keto-amides with all-carbon quaternary centers at the alpha position. [ABSTRACT FROM AUTHOR]

Metal-free, photoredox-catalyzed aromatization-driven deconstructive functionalization of spiro-dihydroquinazolinones with α-CF 3 alkenes is presented. The readily available spiro-dihydroquinazolinones reacted efficiently with α-CF 3 alkenes during photocatalysis to give the gem -difluoroallylated and the CF 3 -containing quinazolin-4(3 H )-ones in good yields with excellent chemoselectivity. The selectivity depends on the electron effect of substituents in α-CF 3 alkenes. A wide range of four-, five-, six-, seven-, eight- and twelve-membered spiro-dihydroquinazolinones were compatible with this transformation. The protocol is also characterized by the mild and redox-neutral reaction conditions, good functional group compatibility and excellent atom economy. Mechanistic studies revealed that the reaction proceeds via a radical pathway.

An unprecedented base-promoted multi-component one-pot dearomatization of N -alkyl activated azaarenes was developed, which enabled the synthesis of complex and diverse bridged cyclic polycycles with multiple stereocenters in a highly regio- and diastereoselective manner. Besides, we realized the step-controlled dearomative bi- and trifunctionalization of quinolinium salts. These transformations not only achieved the maximization of the reaction sites of pyridinium, quinolinium and isoquinolinium salts to enhance structural complexity and diversity, but also opened up a new reaction mode of these N -activated azaarenes. A unique feature of this strategy is the use of easily accessible and bench-stable N -alkyl activated azaarenes to provide maximum reactive sites for dearomative cascade cyclizations. In addition, the salient characteristics including high synthetic efficiency, short reaction time, mild conditions and simple operation made this strategy particularly attractive., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)