Pronounced Electronic Effect of Allylic Amino Groups on the π-Facial Stereoselectivity and Reactivity of the Iodoetherification of N-Substituted 3-Amino-4-penten-1-ols

Autor: Zen-ichi Yoshida, Yoshinao Tamaru, Hiroto Harayama, Hirooki Nagaoka, Takashi Bando
Rok vydání: 2006
Předmět:
Zdroj: Liebigs Annalen. 1996:223-234
ISSN: 1099-0690
0947-3440
Popis: The iodoetherification of N-substituted 3-amino-4-penten-1-ol (1) [I2 and NaHCO3 (2 equivalents each) in ether/H2O at 0°C], providin the mixtures of N-substituted cis- and trans- 3-amino-2-iodomethyltetrahydrofurans (9), displayed diastereoselectivity which was found to correlate with the Taft σ* constants of the N-substitutents (SO2CF3, SO2Me, SO2-P-Tol, COPh, COMe): log(cis-9/trans-9) = 0.616σ* – 1.67 (r = 0.997). the 2-methyl-substituted derivatives of 1 exhibit larger ρ values, while for the 4-methyl derivative of 1 is approximately zero, Iodoetherification of a variety of N-tosyl (σ* = 3.32) 1- and 2-substituted derivatives of 1 afforded the corresponding cis isomers with 70 – >95% selectivities, while that of the N-benzoyl (σ* = 2.20) derivatives furnished the trans isomeres with 70–80% selectivities. These results are interpreted in terms of a πC(4)–C(5)-σ*C(3)–N interaction of conformer II. The N-CO2R (R = Et, t-Bu) and N-SO2NMe2 derivatives of 1 display anomalously high cis selectivities.
Databáze: OpenAIRE
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