A New Alkylation Method for Heptalene-4,5-dicarboxylates and of One of Their Pseudoester Forms
作者:Khaled Abou-Hadeed、Zoltàn A. Molnar、Pinar Göksaltık、Roland W. Kunz、Anthony Linden、Hans-Jürgen Hansen
DOI:10.1002/hlca.201100510
日期:2012.6
Dimethyl heptalene‐4,5‐dicarboxylates 1 The locants of heptalene itself are maintained throughout the whole work. See footnote 4 in [1] for reasoning. undergo preferentially a Michael addition reaction at C(3) with α‐lithiated alkyl phenyl sulfones at temperatures below −50°, leading to corresponding cis‐configured 3,4‐dihydroheptalene‐4,5‐dicarboxylates (cf. Table 1, Schemes 3 and 4). The corresponding
二甲基庚烯-4,5-二羧酸盐 1庚烷本身的定位剂在整个工作过程中都得到维护。有关推理,请参见[1]中的脚注4。在低于50° C的温度下,优先在C(3)与α-锂化的烷基苯基砜进行迈克尔加成反应,从而导致相应的顺式构型的3,4-二氢庚二烯-4,5-二羧酸酯(参见表1,方案3和4)。相应的庚二烯-4,5-二羧酸二甲基庚酯的呋喃基呋喃-1-酮假酯(方案5)几乎仅在呋喃酮基团的C(1)处与[(苯磺酰基)甲基]锂反应(方案6)。与这种预期的行为相反,只要七聚呋喃-1-酮的C(5)处会吸收1- [苯磺酰基)乙基]锂,只要它们在C(11)处带有Me基(方案6和7)。在THF中用MeONa / MeOH处理后,1,4和1,6加成产物消除了苯磺酸盐,从而分别导致了3和4烷基化的二甲基庚烯-4,5-二羧酸盐(方案8 – 13)。亲核试剂的固有的手性heptalenes的加成反应的结构进行详细讨论(参见方案14 -