Silver‐Catalyzed [2+1] Cyclopropenation of Alkynes with Unstable Diazoalkanes: N‐Nosylhydrazones as Room‐Temperature Decomposable Diazo Surrogates

Abstract

The [2+1] cycloaddition of alkynes with diazo compounds represents one of the most powerful and reliable methods for the construction of cyclopropenes. However, it remains a formidable challenge to accomplish the cyclopropenation of alkynes with non-stabilized diazoalkanes, owing to the fact that such compounds are unstable and prone to detonation. Herein, we report a general silver-catalyzed cyclopropenation reaction of alkynes with unstable diazoalkanes, by for the first time the discovery and application of N-nosylhydrazones as room-temperature decomposiable diazo surrogates. This method allows for the efficient assembly a wide variety of cyclopropene derivatives that are otherwise difficult to access by conventional methods.

Silver-Catalyzed Regio- and Stereoselective Formal Carbene Insertion into Unstrained C−C σ-Bonds of 1,3-Dicarbonyls

“…However, the process still has certain deficiencies like the need to synthesize and handle potentially toxic and explosive diazo compounds and the fact that the C-C bond cleavage is limited to 1,3-diketones. As part of our continued interest in the silver-catalyzed activation of diazo compounds ( Liu et al., 2017a , Liu et al., 2017b , Liu et al., 2018 ), we here report the silver-catalyzed formal carbene insertion into the unstrained C−C(=O) bonds of 1,3-dicarbonyls ( Xi et al., 2014 ), using N -nosylhydrazones ( Xia and Wang, 2017 , Xiao et al., 2013 , Shao and Zhang, 2012 , Barluenga and Valdés, 2011 ) as diazo surrogates ( Figure 1 C). This represents the first example of the homologation of acyclic ketones with aryldiazomethanes ( Candeias et al., 2016 , Xia et al., 2013 ) and offers a straightforward route to construct synthetically useful polysubstituted 1,4-dicarbonyls, which can be difficult to synthesize by other approaches ( DeMartino et al., 2008 , Yoo et al., 2010 , Liu et al., 2011 ).…”

Catalyst‐Dependent Chemoselective Formal Insertion of Diazo Compounds into C−C or C−H Bonds of 1,3‐Dicarbonyl Compounds

“…[8] We targeted an ew method to achieve the insertion of diazo-derived carbenoids into acyclic CÀCbonds. [9] Based on achievements in the silver-catalyzed activation of diazo compounds by our group [10] and others, [11] we questioned whether inexpensive silver catalysts could be used to mediate C À Ci nsertion. Although coinage metals have been extensively exploited in the alkylation of C(sp) À H, [12] C(sp 2 ) À H, [13] and C(sp 3 ) À H [14] bonds with diazo compounds [15] (e.g.,S his report on an alkylation reaction;F igure 1a), [16a] equivalent CÀCi nsertions are unknown.…”

Gold and TfOH‐Cocatalyzed Tandem Reaction of ortho‐Akynylarylaldehydes with Cyclopropenes: an Efficient Route to Functionalized Benzo[7]annulene Derivatives

“…First, the reactions of 2‐(phenylethynyl)benzaldehyde ( 1a ) and different cyclopropenes 8 ,[8b] 9 and 10a were carried out, respectively. Several metal catalysts such as AuCl 3 , AgNTf 2 , Cu(OTf) 2 and ZnCl 2 were screened, indicating that no desired product was obtained under various conditions.…”