80°C
△80℃ HH
(乙)4n+2个π电子体系 CH CH CH,÷ CH3 hl H H CH3 CH (Z, Z,E)-2, 4, 6-octatriene CH CH CH H CH3 H CH 3 H CH (E, L,E)-2, 4, 6-octatriene
(乙)4n+2个π电子体系 (Z,Z,E)-2,4,6-octatriene (E,Z,E)-2,4,6-octatriene △ CH3 HCH3 H CH3 HHCH3 CH3 HCH3 H CH3 CH3 HH △ CH3 HCH3 H hνhν CH3 HCH3 H
H H H H H H
HH △ HH ×△ HH △ H H △ H H
(2)环加成反应 2+1环加成: CH,=CH, R2C RR 2+2环加成:CH2=CH2+CH2=CH2→ 4+1环加成:CH2=CH—CH=CH2 2+ so sO 13偶极加成:cH2-N=N+星 HCO,Me CoMe CHCO, Me N COMe 41环加成:CH2=CH-CH=CH2+CH2=CH2→
(2)环加成反应 CH2 CH2 R2C: R R CH2 CH2 CH2 CH2 [2+1]环加成: [2+2]环加成: [4+1]环加成:CH2 CH CH CH2 SO2 SO2 CH2 N N CHCO2Me CHCO2Me N N CO2Me CO2Me 1,3-偶极加成: [4+1]环加成:CH2 CH CH CH2 CH2 CH2
新键的生成在反应体系的同面叫同面环加成 (suprafacial cycloaddition H H2C CH 3 H H 2s +] H3C CH H H CH H2C CH2 HrC CH 2s切2s CH3 CH C=C H一般环加成为同面环加成
新键的生成在反应体系的同面叫同面环加成 (suprafacial cycloaddition) C C H CH3 H H3C C C H CH3 H H3C hν π s 2 2 π s CH3 CH3 CH CH3 3 C C H3C H CH3 H C C H CH3 H H3C CH3 CH3 CH3 CH3 π s 2 2 π s hν 一般环加成为同面环加成