Organoboranes for synthesis. 7. An improved general synthesis of primary amines from alkenes via hydroboration-organoborane chemistry
✍ Scribed by Herbert C Brown; Kee-Won Kim; Morris Srebnik; Singaram Bakthan
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- French
- Weight
- 665 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Trforganylboranes, R3B, and diorganylborinic esters, R2BOR', re--readily with preformed chloramine or hydroxylamine-0-sulfonic acid to produce the corresponding primary amines, RNH2. However, the product of the reaction following hydrolysis is the boronic acid, RB(oH)2, limiting the yield to 67% for R3B and to 50% for R BOR'. This problem has now been overcome with the help of lithium dimethy borohydride. T readily converted in situ to dimethylborane. The hydroboration of representative alkenes by dimethylborane provides the corresponding monoorganyldimethylborane, RMe2B. Treatment of this intermediate with hydroxylamine-0-sulfonic acid provides the desired amines, RNH2, in isolated yields of 73% to 95%. The reaction oroceeds with complete retention, reproducing the precise structure of the organic group in the organoboranes, RMe2B. The oxidation of triorganylboranes by alkaline hydrogen peroxide is applicable to organoboranes with a wide range of structure (eq l).2 The quantitative and proceeds with complete retention of configuration (eq 2).3 The reaction R3B + 3 H202 + NaOH an ideal reaction, widely reaction is essentially --> 3 ROH t NaB(OH)4 (1) can accommodate an exceptionally wide variety 9