Observations concerning the synthesis of heteroatom-containing 9-membered benzo-fused rings by ring-closing metathesis
作者:Blessing A. Aderibigbe、Ivan R. Green、Tanya Mabank、Mari Janse van Rensburg、Garreth L. Morgans、Manuel A. Fernandes、Joseph P. Michael、Willem A.L. van Otterlo
DOI:10.1016/j.tet.2017.06.039
日期:2017.8
NR,NR or O,NR where R = Ts or Boc). As previously observed in the literature, many of the dienes did not give the expected ring-closed product. However, a number of the desired products did form, namely with the 1,2-dihydrobenzo[c][1,5]oxazonin-7(5H)-one, 5,7-dihydrobenzo[b][1,5]oxazonine-6(2H)-carboxylate and 2,5,6,7-tetrahydrobenzo[b][1,5]oxazonine cores, albeit in poor yields. Rather surprisingly
易于合成一组具有1,9关系的苯并稠合的二烯,其中包含各种氮和氧杂原子。然后将这些二烯用Grubbs第二代催化剂处理,目的是合成含有两个杂原子(O,O,NR,NR或O,NR,其中R = Ts或Boc)的9元苯氮杂环。如先前在文献中观察到的,许多二烯没有给出预期的闭环产物。但是,确实形成了许多所需产物,即与1,2-二氢苯并[ c ] [1,5]恶唑嗪-7(5 H)-一,5,7-二氢苯并[ b ] [1,5]形成。恶唑啉-6(2 H)-羧酸盐和2,5,6,7-四氢苯并[ b] [1,5]恶唑啉核,尽管收率低。令人惊讶地,N-烯丙基-N-(2-(N-烯丙基-4-甲基苯基磺酰胺基)苄基)-4-甲基苯磺酰胺骨架产生所需的闭环的1,6-二甲苯基-2,5,6,7-四氢-1 H-苯并[ b ] [1,5]重氮高产。此外,当用催化剂[RuClH(CO)(PPh 3)3 ]处理时,烯烃仅与苄基NTs基团异构化成共轭,而不与苯基NTs基团共轭,得到1