Asymmetric cyclization of 3,4-dihydro-2-vinyl-2H-1,4-benzoxazine catalyzed by palladium-BHMP catalyst

The reaction of 1,4-diacetoxy- cis-2-butene 2a with 2-(benzylamino)phenol 3 in THF in the presence of Et 3N and a catalytic amount of Pd(0)-BHMP-β-Ala 1c gave optically active 4-benzyl-2-vinylbenzoxazine of up to 56.2%ee. The reaction of ( Z)-2-butene-1,4-diylbis(methylcarbonate) 2b instead of 2a wi...

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Bibliographic Details
Published in:Tetrahedron: asymmetry 1996-02, Vol.7 (2), p.403-406
Main Authors: Yamazaki, Akira, Achiwa, Issei, Achiwa, Kazuo
Format: Article
Language:English
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Summary:The reaction of 1,4-diacetoxy- cis-2-butene 2a with 2-(benzylamino)phenol 3 in THF in the presence of Et 3N and a catalytic amount of Pd(0)-BHMP-β-Ala 1c gave optically active 4-benzyl-2-vinylbenzoxazine of up to 56.2%ee. The reaction of ( Z)-2-butene-1,4-diylbis(methylcarbonate) 2b instead of 2a with 2-(benzylamino)phenol 3, 4 was obtained with e.e. up to 71.4%. We could improve the enantioselectivity of (R)- 4 by introducing a carboxyl group at the terminal position of the pendant side chain on the bisphosphine ligand and by using a methyl carbonate ester 2b instead of diacetate 2a. Graphic
ISSN:0957-4166
1362-511X
DOI:10.1016/0957-4166(96)00018-3