Gold- and Platinum-Catalyzed Formal Markownikoff’s Double Hydroamination of Alkynes: A Rapid Access to Tetrahydroquinazolinones and Angularly-Fused Analogues Thereof

Abstract

A highly efficient gold(I)- and platinum(II)-catalyzed process for formal Markownikoff's double hydroamination of alkynes tethered with hydroxyl group has been developed. The method was shown to be applicable to a broad range of 2-aminobenzamides and alkynols leading to the formation of multiply substituted tetrahydroquinazolinones. Interestingly, when Pt(IV)Cl(4) catalyst was employed, cyclic angularly fused compound was obtained.

Alkyne hydroamination triggered cyclizations: A powerful tool for the construction of biologically important structural motifs

“…The reactions of amino group containing aromatics 98/99 with alkynols 100 were achieved in methanol to give substituted pyrrolo [1,2- [69].…”

Scandium triflate catalyzed unexpected cleavage of C-C bonds in ynones

“…[13][14][15][16] During these studies, we had occasion to examine the reaction of δ-hydroxyalkynones A with 2-aminophenyl pyrrole B in MeOH under microwave conditions (Scheme 1). The formation of polyheterocycle 17 C was expected based on the assumption that endo-cyclization might favour over to exocyclization due to the ring strain of incipient methyleneoxetane.…”

AuI‐Catalyzed Direct Hydroamination/Hydroarylation and Double Hydroamination of Terminal Alkynes

“…[22] Therefore, with toluene as solvent, a series of π-acidic catalysts were screened, and the results are outlined in Table 1. Based on our earlier report, [15,16] the reaction was initially conducted by using platinum catalysts, such as PtCl 2 , PtBr 2 or PtCl 4 ; however, lower yields were obtained in all cases (Entries 1-3). The catalysts AgOTf and Cu(OTf) 2 gave 3a in 20 and 40 % yields, respectively (Entries 4 and 5).…”

“…A reaction as envisioned could be considered as a hydroamination/hydroarylation (when Nu = Ar) and double hydroamination (when Nu = NH 2 ), which would provide access to a wide variety of nitrogen-containing heterocycles. (2) Previously, we reported double hydroamination [15] and hydroamination/hydroarylation [16] cascade reactions of terminal alkynes bearing a hydroxy group in the proximity ( Figure 1, path a). A proximal hydroxy group proved to be necessary for the reaction to occur; alkynes with no hydroxy group in the tether (e.g., 1-octyne) failed to react.…”