# NaHMDS/B(C6F5)3-promoted diastereoselective Friedel–Crafts alkylation of indoles/pyrroles with N-tert-butanesulfinylimines: towards the asymmetric synthesis of bisindole alkaloid Calcicamide B

## TL;DR

The paper introduces a new method for asymmetric Friedel–Crafts alkylation to synthesize chiral compounds, including the anti-tumor alkaloid Calcicamide B.

## Contribution

A novel diastereoselective Friedel–Crafts alkylation method using NaHMDS/B(C6F5)3 and chiral imines for asymmetric synthesis.

## Key findings

- Enantioenriched α-(3-indolyl)glycine and α-(2-pyrrolyl)glycine derivatives were effectively produced.
- The method enabled the first asymmetric total synthesis of the bisindole alkaloid Calcicamide B.

## Abstract

This study proposed an innovative and pragmatic approach to the asymmetric Friedel–Crafts reaction by employing indoles/pyrroles and chiral N-tert-butanesulfinylimines promoted by NaHMDS/B(C6F5)3. This method effectively produces enantioenriched α-(3-indolyl)glycine and α-(2-pyrrolyl)glycine derivatives, which can be readily transformed into the crucial chiral diamine skeletons. The first successful asymmetric total synthesis of marine-derived anti-tumor bisindole alkaloid Calcicamide B was achieved by employing this reaction as a crucial chiral control step.

This study proposed an innovative and pragmatic approach to the asymmetric Friedel–Crafts reaction by employing indoles/pyrroles and chiral N-tert-butanesulfinylimines promoted by NaHMDS/B(C6F5)3.