Benzo[a]heptalenes from Heptaleno[1,2-c]furans. Part 2
作者:Peter Uebelhart、Christophe Weymuth、Anthony Linden、Hans-Jürgen Hansen
DOI:10.1002/hlca.200790069
日期:2007.4
regioselective ring opening to the 3-hydroxy-substituted benzo[d]heptalen-2-yl carbamate 2,3-endo-9b (Scheme 3). The latter was O-methylated to 2,3-endo-(P*)-10b. The further way, to get finally the benzo[a]heptalene 13b with MeO groups in 1,2,3-position, could not be realized due to the fact that we found no way to cleave the carbamate group of 2,3-endo-(P*)-10b without touching its 1,4-epoxy bridge
在“第2部分”中显示,庚烷[1,2- c ]呋喃1在呋喃环上的Diels–Alder型[4 + 2]环加成反应中与碳酸亚乙烯酯(VC),苯磺酰基丙二烯(PSA)热反应,α-(乙酰氧基)丙烯腈(AAN)和(1 Z)-1,2-双(苯磺酰基)乙烯(ZSE)生成相应的1,4-环氧苯并[ d ]庚烷(参见方案1,5, 6和8)。的热反应1A和1B与VC在130°和150°分别引线主要以2,3-内切-cyclocarbonates 2,3-内切-图2a和-图2b和少量的2,3 exo- cyclocarbonates 2,3- exo - 2a和-2b。在一些情况下,分离并表征了(P *)-和(M *)-构型的差向异构体并进行了表征(方案1)。2,3- endo - 2的碱催化裂解得到相应的2,3-二醇3,其分别通过其二糖基化物4的还原裂解分别转化为苯并[ a ]庚烷5a和5b(方案2)。在另一个反应顺序中,2