CHEM01200604012 Dibakar Goswami - Homi Bhabha National ...

6 1.2 In (2.0) H 2 O LiCl+ KI 14 72 3.7: 52.3:44.0
7 3.0 In (5.0) H 2 O LiCl+ KI 14 72 3.7: 52.3:44.0
8 3.0 In (5.0) THF -- 12 NR d --
9 4 Ga (2.5) H 2 O -- 20 NR d --
10 3.5 Ga (2.5) THF KI+LiCl 10 55 5.0: 35.0: 60.0
11 1.2 In (2.0) [bmim][Br] -- 4 81 9.3:13.4:77.3
12 1.2 Ga (1.0) [bmim][Br] -- 5 82 3.0 :5.0 :92.0
13 4.0 Bi (2.5) H 2 O -- 12 67 7.0: 31.0: 62.0
14 3.5 Bi (2.5) THF KI+LiCl 20 NR --
15 1.2 Bi (1.0) [bmim][Br] -- 3 73 11.4:82.6 :4.0
a The reactions were carried out at 2 mmol scale. b The yields refer to those of isolated pure
isomers. c The isomeric ratios were determined from the isolated yields. d NR: no reaction.
We then attempted crotylation of carbonyls in these three solvents using Bi metal.
When Bi was used for crotylation of 1 in H 2 O, the reaction proceeded with moderate yield
and diastereoselectivity even with high excess of the reagents (entry 13, Table III.2.2). No
reaction was observed in THF even after metal activation with KF (entry 14, Table
III.2.2). However, to our delight, the reaction in [bmim][Br] was very fast, and could be
carried out with stoichiometric amounts of the reagents (entry 15, Table III.2.2).
Strikingly, this yielded 69b as the major diastereomer, for which this reaction became
important from preparative point of view.
The reactions of 78a with 1 using different metals in different solvents were also
studied. In this case also, the reactions were faster in [bmim][Br], without the need of a
metal activator and using stoichiometric amount of the reagents. Also the yields were
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