Retro-ene reactions in heterocyclic synthesis,<b>III</b>. A new route to 4,5-dihydrooxazoles and 5,6-dihydro-4<i>H</i>-1,3-oxazines
作者:Kunio Ito、Shingo Miyajima
DOI:10.1002/jhet.5570340224
日期:1997.3
2- or 1,3-aminoalcohols 3 to yield oxazolidines 4a-c or tetrahydro-1,3-oxazines 4d,e. The corresponding imino ester 1 (X = NBu-t) also gave 4 on reaction with 3. Compounds 4 on heating at 230° yielded 4,5-dihydrooxazoles 5a-c or 5,6-dihydro-4H-1,3-oxazines 5d,e along with methyl 4-methyl-3-pentenoate (6).
(E)-4,4-甲基二甲基-5-氧代-2-戊烯酸酯(1)与1,2-或1,3-氨基醇3反应生成恶唑烷4a-c或四氢-1,3 -恶嗪4d,e。相应的亚氨基酯1(X = NBu- t)在与3反应时也得到4。在230℃加热下的化合物4产生4,5-二氢恶唑5a-c或5,6-二氢-4 H -1,3-恶嗪5d,e以及4-甲基-3-戊烯酸甲酯(6)。