Cyclization of 1-Bromo-2,7- and 1-Bromo-2,8-Enynes Mediated by Indium
摘要:
[Graphics]The cyclization of 1-bromo-2,7- and 1-bromo-2,8-enynes mediated by indium in DMF produced five- and six-membered cyclic compounds. Although KI was a necessary additive in the cyclization of terminal 1-bromo-2,7-enynes to give the desired products at 25degreesC, reactions of terminal 1-bromo-2,8-enynes and internal 1-bromo-2,7-enynes with indium proceeded at 100degreesC in DMF without KI. After cyclizations, subsequent cross-coupling reaction and iodolysis increase the usefulness of this reaction.
描述了广泛的钯催化的芳基和乙烯基卤化物和烯丙基乙酸酯的区域特异性和立体特异性的5-,6-和7-exo-dig单,双和三环化方法。单环和双环化过程终止于从哌啶甲酸或甲酸钠中捕获氢化物。Tl 2 CO 3的添加导致炔-丙二烯异构化,并且在环化之后导致1,3-二烯,这使Diels-Alder加合物具有良好的收率。
silicon-initiated cascade carbonylativecarbotricyclization (CO-SiCaT) process. It has also been found that the 5-7-5 fused tricyclic products can be obtained from the same type of enediynes and CO through a novel intramolecular [2+2+2+1] cycloaddition process. The characteristics of these two tricyclization processes and the fundamental differences in their reaction mechanisms are discussed. This novel higher-order
Enediynes undergo intramolecular [2+2+2] cycloaddition in the presence of cobalt(II) iodide (CoI2), manganese and an N-heterocyclic carbene (IPr) generated in situ from the corresponding imidazolium salt and butyllithium (BuLi). Polycyclic cyclohexadienes are obtained selectively. This new method represents an interesting alternative to those employing air-sensitive cyclopentadienylcobalt [CpCoL2 (L=CO
In sharp contrast with the standard [2 + 2 + 2] cycloadditionreaction of diyne/ene, cobalt-mediated cycloadditions with γ-alkylidenebutenolide led to unprecedented cobalt(III) polycyclic complexes. A plausible mechanism supported by a computational study based on an unusual fragmentation of the butenolide moiety was postulated to account for this original reaction.
One-step formation of fused tetracyclic skeletons from cyclohexene-diynes and carbon monoxide through Rh(i)-catalyzed [2 + 2 + 2 + 1] cycloaddition reaction
作者:Joseph J. Kaloko、Yu-Han Gary Teng、Iwao Ojima
DOI:10.1039/b909781c
日期:——
Rapid construction of 5-7-6-5 fused tetracyclic carbocycles and heterocycles from cyclohexene-diynes and CO has been achieved in one step through a Rh(i)-catalyzed [2 + 2 + 2 + 1] cycloaddition process.