Table 1.

Investigation of the impact of protective groups on β-selective di-aminofucosylation.

Entry	Substrate	Reaction Condition	Yield	α : β
1		[p-TolSCl + AgOTf]a, DCM	89%	3 : 2
2		[NIS + TfOH]b, DCM	92%	2 : 3
3		[NIS + TfOH], DCM/MeCN = 9/1	90%	2 : 3
4		[NIS + TfOH], DCM/MeCN = 1/1	25%	α only
5		[NIS], DCM	60%	5 : 1
6		[NIS], DCM	<5%	N/A
7		[p-TolSCl + AgOTf], DCM	30%	α only
8		[NIS + TfOH], DCM	80%	3 : 1
9		[NIS + TfOH], DCM	91%	1 : 2
10		[NIS + TfOH], DCM	<5%	N/A
11		[p-TolSCl + AgOTf], DCM	60%	1 : 2.5c

^[a][NIS + TfOH]: NIS, TfOH, 4Å MS, −78°C

^[b][p-TolSCl + AgOTf]: p-TolSCl, AgOTf, 4Å MS, −78°C

^[c]Ratios determined from NMR spectra of the crude reaction mixtures