Thermal [2 + 2] cycloaddition of allenes with an additional multiple bond is described. By simply heating the allenenes or allenynes having a three-atom tether in an appropriate solvent such as dioxane or DMF, the distal double bond of the allenic moiety regioselectively participates in the cycloaddition to form bicyclo[4.2.0]oct-5-ene derivatives in good to excellent yields. In all the reactions of
Palladium(0)-Catalyzed Stereoselective Cyclization of Allenenes: Divergent Synthesis of Pyrrolidines and 3-Azabicyclo[3.1.0]hexanes from Single Allenenes
Two novel palladium(0)-catalyzedcyclizations of allenenes are described. Treatment of allenenes such as N-(1-alkyl-2,3-butadienyl)-N-allylsulfonamide with an aryl halide and K2CO3 in the presence of a catalytic amount of Pd(PPh3)4 in dioxane affords 2,3-cis-pyrrolidines in a stereoselective manner. In sharp contrast, cyclization of the same allenenes using catalytic Pd2(dba)3·CHCl3 in the presence
描述了两个新的钯(0)催化的烯丙基环化。在催化量的Pd(PPh 3)4存在下于二恶烷中用芳基卤化物和K 2 CO 3处理亚勒烯,例如N-(1-烷基-2,3-丁二烯基)-N-烯丙基磺酰胺,得到2,以立体选择性方式的3-顺-吡咯烷。与之形成鲜明对比的是,在CH 3 CN中存在烯丙基碳酸酯的情况下,使用催化性Pd 2(dba)3 ·CHCl 3催化相同的烯丙烯环化,可选择性地立体生成3-氮杂双环[3.1.0]己烷骨架。
Novel synthesis of chiral terminal allenes via palladium(0)-catalyzed reduction of mesylates of 2-bromoalk-2-en-1-ols bearing a protected amino group, using diethylzinc
A novel palladium(0)-catalyzed synthetic route to a series of chiral terminal allenes bearing an N-protected amino alkyl group has been developed. The palladium(0)-catalyzed reaction of mesylates of 2-bromoalk-2-en-1-ols bearing an aminofunctionality, with diethylzinc affords the corresponding terminal allenes in good yields. Both (E)- and (Z)-bromomesylates can equally be used for the present reaction