Abstract
An efficient, mild and inexpensive protocol for the stereoselective construction
of cyanohydrins in hindered, and in some cases, multifunctional cyclic ketones has
been established.
Key words
cyanohydrin - diastereoselectivity - ketones
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A typical experimental procedure is as follows: to the ketone (2-3 mmol) was added
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These diastereomers were readily distinguishable by 1 H NMR spectroscopy: for 6a at δ = 2.9 and 3.4 ppm (J = 13.6 Hz) and for 7a , the benzylic resonances appeared as a dd at δ = 2.5 and 3.6 ppm (J = 13.2 Hz).
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Additional support for the fact that lactam 10 was epimeric at C-7 came from a consideration of 13 C NMR values: the 13 C nitrile resonances for the two disatereomers of 4a were at δ = 120.16 and 118.99 ppm, for 4b were at δ = 122.32 and 119.32 ppm, and for 6a and 7a were at δ = 119.08 and 118.86 ppm. For cyanohydrin 10 , the corresponding values were 114.8 and 114.9 ppm, and for the single diastereomers
11 and 13 , the values were 115.0 and 116.2 ppm.
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