Unusual Strain-Releasing Nucleophilic Rearrangement of a Bicyclo[2.2.1]heptane System to a Cyclohexenyl Derivative
作者:Mansoureh Karimiahmadabadi、Andras Földesi、Jyoti Chattopadhyaya
DOI:10.1021/jo301871d
日期:2012.11.2
We report an unusual strain-releasing reaction of 1-mesyloxy-8,7-dimethylbicyclo[2.2.1]heptane (3) by a base-promoted substitution at the chiral C3 followed by spontaneous concerted ring opening involving the most strained C2–C3–C4 bonds (with bond angle 94°) and the C2 bridgehead leading to anti–endo elimination of the C1-mesyloxy group by the conjugate base of adenine or thymine to give two diastereomeric
我们报告了一个不寻常的应变释放反应,通过手性C3的碱促进取代作用的1-甲氧甲氧基-8,7-二甲基双环[2.2.1]庚烷(3),随后发生自发一致的开环,涉及最紧张的C2-C3 1 -C 4个键(与键角94°),C2桥头堡导致抗-内切消除C1-甲磺酰氧基的由腺嘌呤的共轭碱或胸腺嘧啶,得到两种非对映体C3'(小号)和C3'([R )衍生物1-胸苷基和9-腺嘌呤基环己烯的结构:3→T-4a + T-4b和3→A-5a + A-5b。这些产品已通过详细的1D和2D NMR进行了明确表征(J耦合常数和nOe分析),质量和UV光谱。已经有证据表明这些非对映体C3'(起源小号)和C3'([R)1- thyminyl和9-腺嘌呤基的环己烯衍生物,从3是最可能形成在S一个三角双锥中间体的重排机制Ñ 2位移开环反应。