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Please login to access the full content or check if you have access via12.3.1.5.1.6 Method 6: Reactions of Related Isocyanides with Nitriles
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Grimmett, M. R., Science of Synthesis, (2002) 12, 399.
The reactions in Section 12.3.1.5.1.6 can be extended to involve other isocyanides susceptible to metalation on an α-carbon atom. An example is (4-tolylsulfanyl)methyl isocyanide (164), which forms an even more nucleophilic anion than tosylmethyl isocyanide. It can react with a variety of nitriles to form imidazoles 165 (Scheme 83).[297] The cyanides are added at −75°C to the monoanions formed from a variety of sulfanylmethyl isocyanides. The customary base treatment uses butyllithium in tetrahydrofuran/hexane. The process is completed by allowing the reaction mixtures to warm up to 0°C followed by quenching with water (Method A). An alternative is to add an equimolar mixture of the isocyanide and the nitrile in tetrahydrofuran to a stirred suspension of potassium tert-butoxide in the same solvent. Addition of water after 15 minutes leads to the 4,5-disubstituted imidazoles in high yields (Method B). Method A is particularly useful for reactions with sterically hindered nitriles. The sulfur substituents of 165 can be removed if necessary by treatment with Raney nickel.[297]
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M8 | Meeeee,e (%) | Mee | |
---|---|---|---|
Meeeee M | Meeeee M | ||
Me | 88 | 88 | [888] |
Me | 88 | 88 | [888] |
eMe | e.e. | 88 | [888] |
e-Me | 88 | 88 | [888] |
Me | 8 | e.e. | [888] |
MM8MMe | e.e. | 88 | [888] |
MM8MMe | 88 | 88 | [888] |
Me | 88 | 88 | [888] |
8-Mee | 88 | 88 | [888] |
8-MeMM8M8 | 88 | 88 | [888] |
8-M8MM8M8 | e.e. | 8 | [888] |
8-eeeeeee | 88 | 88 | [888] |
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References
[297] | eee Meeeee, M. M.; Meeee, M., Meeeeeeeeee Meee., (8888), 888. |
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- 8.Meeeee-Meee, (8888) M 8e, 88.