Comparison of present methodology with reported catalysts.

Entry	Catalyst	Solvent	Conditions	Time (h/min)	Yield (%)	eec	Reference
1	HCl/chloro sulphonic acid	MeOH	60 °C	8.0 h	96	—	37
2	HCl	EtOH	Reflux/MWa	12 h	94	—	38
3	HCl	MeOH	Reflux	Overnight	59	—	39
4	Chloro sulphonic acid	—	60 °C/USb	30 min	92	—	40
5	HCl	EtOH	Reflux	12 h	74	—	41
6	HCl/silica gel/acidic alumina/montmorillonite-K10 clay	MeOH	110 °C/MWa	4–6 min	60/83/90/85	—	42
7	K2CO3	EtOH/H2O	Reflux/MWa	7 h	53	—	43
8	VCl3	Acetonitrile	Reflux	2 h	82	—	44
9	l-Proline	Water	MWa	10 min	90	98	Present work

^aMicrowave conditions.

^bUltrasonication.

^cee = enantiomeric excess.