A novel cascade phosphorylation/cyclization of indole-containing propargylic alcohols with P(O)-H species under mild conditions is described. This strategy provides an efficient and practical approach to obtaining various valuable 6-phosphoryl-6-vinyl indeno2,1-bindoles via the construction of one C-P bond and one C-C bond in a single procedure. This reaction proceeded via a phosphorylated allene initiating the subsequent highly regioselective 5-exo-trig cyclization to afford the target products, which first demonstrates the cyclization as a new reaction mode compared with conventional cyclization pathways.
Liang et al. (Wed,) studied this question.