- Complementary diastereoselectivity in the intermolecular addition of titanium and magnesium naphtholates to asymmetric lactaldehydes
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Addition of 7-benzyloxy-4,5-dimethoxy-1-naphthol 3 as its triisopropoxytitanium naphtholate to (2R, 1′R or S)-2-(1′-ethoxyethoxy)propanal 4 afforded solely (15, 2R, 1″R or S)-1-(7′-benzyloxy-4′,5′-dimethoxy-1′-hydroxy-2′- naphthyl)-2-(1″-ethoxyethoxy)propan-l-ol 5, being the erythro product arising from anti addition. Complementary reaction of the naphthol 3 as its bromomagnesium naphtholate with aldehyde 4 gave rise solely to the alternative (1R, 2R, 1″R or S) diastereomer 6. The naphthol 3 was prepared through the completely regioselective addition of 2-methoxyfuran 9 to 5-benzyloxy-3-methoxydehydrobenzene 8. This differentially protected bisalkoxybenzyne was conveniently prepared from vanillin. The Royal Society of Chemistry 1999.
- Giles, Robin G. F.,Joll, Cynthia A.,Sargent, Melvyn V.,Tilbrook, D. Matthew G.
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p. 3029 - 3038
(2007/10/03)
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