. Author manuscript; available in PMC: 2018 Jun 1.

Published in final edited form as: Nat Chem. 2017 Jul 17;9(12):1269–1275. doi: 10.1038/nchem.2816

Table 2.

Studies to identify an effective chiral catalyst.



Entry	Ligand	Conv. (%)^*	Yield (%)^†	e.r.^††
1	R-binap	70	65	44:56
2	5a	55	51	18:82
3	5b	65	51	19.5:80.5
4	5c	29	27	69:31
5	6	80	51	40:60
6	7a	>98	65	55:45
7	7b	54	51	95:5

Reactions were carried out under N₂ atmosphere; 1.2:1 ratio of ketimine:allene was used.

Conversion (consumption of allene; (includes desired and decomposition products) and d.r. was measured by analysis of 400 MHz ¹H NMR spectra of unpurified mixtures; variance of values is estimated to be <±2%.

^†

Yield of isolated and purified products (<±5%).

^††

Enantiomeric ratio (e.r.) values were determined by HPLC analysis (<±1%) (see the Supplementary Information for details).

Abbreviations: TBS, tert-butyldimethyl silyl; pin, pinacolato; Mes, 2,4,6-Me₃C₆H₂; Cy, cyclohexyl; binap, 2,2’-bis(diphenylphosphino)-1,1’-binaphthalene.