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. Author manuscript; available in PMC: 2014 Sep 30.
Published in final edited form as: Synthesis (Stuttg). 2014 Jun 1;46(11):1539–1546. doi: 10.1055/s-0033-1340982

Table 1.

Optimization of the Reaction Conditions

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graphic file with name emss-60520-t0007.jpg
Entrya Catalyst Solvent Time (d) Additiveb Yieldc (%) eed (%)
1 3a CH2Cl2 3 – 18 n.d.
2 3b CH2Cl2 3 – – n.d.
3 3c CH2Cl2 3 – – n.d.
4 3d CH2Cl2 3 – 6 n.d.
5 3e CH2Cl2 3 – 47 97
6 3e CH2Cl2 5 – 55 87
7 3e EtOH 5 – 21 69
8 3e i-PrOH 5 – 49 73
9 3e EtOHe 2 – 38 32
10 3e i-PrOHe 2 – 32 47
11 3e CH2Cl2 5 NaOAc 63 97
12 3e CH2Cl2 5 K2CO3 39 53
13 3e CH2Cl2 5 Na2CO3 27 58
14f 3e CH2Cl2 6 NaOAc 45 94
15g 3e CH2Cl2 6 NaOAc 60 94
16 3e CH2Cl2 3 NaOAc 47 93
a

Reaction conditions: 0.3-mmol scale using 1a (1 equiv), 2a (2 equiv), catalyst 3a–e (20 mol%), solvent (1 mL), r.t. Only one diastereomer was observed.

b

20 mol% of the additive was used.

c

Yield of the isolated product 4a after flash column chromatography.

d

Determined by HPLC on a chiral stationary phase; n.d. = not detected.

e

The reaction was heated to reflux for 2 d.

f

A ratio 1.6:2 of 1a/2a was used.

g

A ratio 1:2.5 of 1a/2a was used.