Table 1.

Initial Optimizations.

entry	Eq. NaBH4	Solvent	Time (hours)	% NMR Yield	% Conversion MPFBb
1	0.50	MeOH	10	0	~100
2	0.50	EtOH	10	6	72
3 a	0.50	THF	10	<2	<2
4 a	0.50	DME	10	46	46
5	0.50	DMF	10	70	72
6	0.50	DMSO	10	97	98
7	0.33	DMSO	2	23	23
8	0.66	DMSO	2	43	43
9	1.00	DMSO	2	99	99
10	2.00	DMSO	2	99	99

^aReactions were run as suspensions.

^bDetermined using ¹⁹F NMR.