在氮原子上被不同的π-亲核试剂取代的噻唑烷二酮3-8的区域选择性NaBH 4 / H +还原以良好的产率提供羟基内酰胺9-14。后面的化合物是α-酰化铵离子16的极好的前体,可以在HCOOH中进行立体选择环化,以产生具有不同结构的新型杂环系统。由于闭环中的立体电子控制,很容易实现立体选择性合成,例如8a到24的转换。
A new strategy to construct a CC–CF3 subunit via CuBr-catalyzed domino reaction of homopropargyl amines: an efficient synthesis of trifluoromethyl containing building blocks 4-trifluoromethyl-2,3-dihydro-pyrroliums
A new strategy for the construction of a CCâCF3 subunit has been developed via CuBr-catalyzed domino cyclizationâtrifluoromethylation of homopropargyl amines with Umemoto's reagent. 4-Trifluoromethyl-2,3-dihydro-pyrroliums were produced in high yields. The usefulness of these products has been demonstrated by the transformation of them into various other trifluoromethylated molecules.
Oxidative Prins and Prins/Friedel–Crafts cyclizations for the stereoselective synthesis of dioxabicycles and hexahydro-1H-benzo[f]isochromenes via the benzylic C–H activation
作者:B. V. Subba Reddy、Prashant Borkar、J. S. Yadav、P. Purushotham Reddy、A. C. Kunwar、B. Sridhar、René Grée
DOI:10.1039/c1ob06489d
日期:——
stereoselectivity. Aryl tethered homoallylbenzyl ethers such as benzyl ethers of (E)- and (Z)-6-arylhex-3-enyl alcohols undergo a tandem Prins/Friedel–Crafts cyclization in the presence of stoichiometric amounts of DDQ and SnCl4via the benzylic C–H bond activation to furnish the corresponding trans- and cis-fused hexahydro-1H-benzo[f]isochromenes in good yields with complete stereoselectivity.
(In)和(z)-hex-3-en-1,6-二醇和hept-3-en-1,7-二醇的1-苄醚在In( OTF)3通过顺序C-H键活化和分子内的环化的Prins,得到相应的反式-和顺-融合六氢-2- ħ -呋喃并[3,2- c ^ ]吡喃和octahydropyrano [4,3- b ]吡喃分别以良好的产率和优异的立体选择性。芳基束缚的高烯丙基苄基醚,例如(E)-和(Z)-6- arylhex -3-烯基醇经过串联普林斯/弗里德尔-克拉夫茨环化反应中的化学计量的量和DDQ的SnCl存在4经由苄基C-H键活化,以提供相应的反式-和顺式-融合六氢1 H-苯并[ f ]异色酮的收率高,具有完全的立体选择性。
Tandem Prins/Friedel–Crafts Cyclization for Stereoselective Synthesis of Heterotricyclic Systems
作者:B. V. Subba Reddy、Prashant Borkar、J. S. Yadav、B. Sridhar、René Grée
DOI:10.1021/jo201027u
日期:2011.10.7
Homoallylic substrates such as (E)-6-arylhex-3-enyl alcohols, N-tosylamides, and thiols undergo smooth cross-coupling with various aldehydes in the presence of 10 mol % Sc(OTf)3 and 30 mol % TsOH to afford the trans-fused hexahydro-1H-benzo[f]isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes, respectively. However, the cross-coupling of (Z)-olefins such