Unexpected stereoselective 6-exo versus 7-endo aryl radical cyclisation controlled by positional isomers in a chiral octahydro-1,3-benzoxazine moiety

Synlett

Volumn , Issue 12, 1997, Pages 1391-1392

  Andrés, Celia ^a   Duque Soladana, Juan P ^a   Iglesias, Jesús M ^a   Pedrosa, Rafael ^a  

^a UNIVERSITY OF VALLADOLID   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0002665191     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1997-1045     Document Type: Article

References (31)

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2. (b) D. P. Curran in Comprehensive Organic Synthesis, Pergamon, Oxford, 1991, vol. 4, chapter 4.
3. Examples of addition to allenes, aldehydes and oximes are known: (a) T. Balasubramanian, K. K. Balasubramanian, Synlett 1994, 946 and cited references.
4. (b) J. W. Grissom, D. Klingberg, S. Meyenburg, B. L. Stallman, J. Org. Chem. 1994, 59, 7876.
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24. Typical procedure for radical cyclisations: To a boiling solution of 1 or 3 in dry, degassed benzene (0.02M and 0.1M concentration were tested) was syringed a mixture of 1.1 mol equiv. of fresh tri-n-butyltin hydride and 10% mol equiv. of AIBN in benzene under inert atmosphere over a period of 6-8 h. The reaction was monitored by TLC until the starting material had disappeared. The solvent was evaporated and the residue redissolved in ether and treated with a 10% KF aqueous solution and stirred overnight. The solids were filtered off and the aqueous layer extracted with ether. Removal of the solvent and flash chromatography on silica gel afforded the final products.
25. 29NO: C, 80.21; H, 9.77; N, 4.68. Found: C, 80.52; H, 9.41; N, 4.66.
26. 29NO: C, 80.21; H, 9.77; N, 4.68. Found: C, 80.50; H, 10.02; N, 4.39.
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