N-alkynylations of substituted pyrroles with 1-bromo-1-alkynes and C-alkylations and C-alkenylations of cyclic 1,2-diketones
Nitrogen-substituted alkynes are a unique class of compounds that have found general use in organic synthesis. The catalytic synthesis of N-substituted alkynes offers a rapid and step-efficient approach for accessing this structural motif. To better understand the synthesis and reactivity profile of N-alkynyl pyrroles, a study of the Cu-catalyzed coupling of pyrroles with 1-bromoalkynes was conducted and the scope uncovered. Subsequently, N-alkynyl pyrroles were applied to the synthesis of pyrrole[2,1-c]oxazin-1-ones and the formal total synthesis of the natural product peramine. Additionally, an N-alkynyl pyrrole was applied toward the synthesis of the pyrrole spiroketal alkaloid shensongine A. The α-alkylation of ketones is an indispensible C-C bond forming process to organic chemists. This process generally involves the formation of an enolate and subsequent alkylation with an electrophile. While very efficient, this series of steps generates a significant amount of waste that is often not on the radar of the typical chemist. Recent work has begun to address this issue resulting in several new “green” α-alkylation procedures. In an effort to better understand the potential application of a C-H activation procedure towards the “green” alkylation of ketones a study of the C-H activation and subsequent alkylation and alkenylation of cyclic 1,2-diketones was conducted.