用浓溶液处理2-(1-羟烷基)丙-2-烯酸甲酯1。用HBr溶液得到(Z)-2-(溴甲基)烷-2-烯酸甲酯2,将其区域选择性地转化成N-取代的甲基(E)-2-(氨甲基)烷-2-烯酸酯3(S N 2反应)并进入ñ取代的甲基2-(1-氨基烷基)丙-2- enoates 4(S ñ 2'反应)。胺对亲核性攻击的区域控制仅通过选择溶剂即可完成,S N 2反应发生在MeCN和S N中。在石油醚中进行2'反应。水解和内酰胺化分别得到β-内酰胺7和8,分别在C(3)处含有外环亚烷基和亚甲基。
γ-Selective Allylation of (<i>E</i>)-Alkenylzinc Iodides Prepared by Reductive Coupling of Arylacetylenes with Alkyl Iodides
作者:Fedor E. Zhurkin、Xile Hu
DOI:10.1021/acs.joc.6b01306
日期:2016.7.1
allylic alkenylation using organozinc reagents are reported. (E)-Alkenylzinc iodides were prepared by Fe-catalyzed reductive coupling of terminal arylalkynes with alkyliodides. In the presence of a copper catalyst, these reagents reacted with allylic bromides derived from Morita–Baylis–Hillman alcohols to give 1,4-dienes in high yields. The reactions are highly γ-selective (generally γ/α > 49:1) and tolerate
A novel intermediate for synthesizing 1 .beta.-alkyl-1-carbapenem, i.e., 4 .beta.-(1 .beta.-alkyl-2-carboxyprop-2-enyl)azetidin-2-one (II), is prepared stereoselectively by treating 4-(leaving group substituted)azetidin-2-one (I) with trans-2-(leaving group substituted)-methyl-3-alkylacrylic acid (III) and a reducing metal. ##STR1## wherein R.sup.1 is hydrogen, alkyl, or substituted alkyl; R.sup.2 is optionally substituted alkyl; R.sup.3 is hydrogen or a carboxy-protecting group; and R.sup.4 and R.sup.5 each is a leaving group.
A series of 28 aryl- and alkyl-substituted isothiouronium salts were readily synthesized in high yields through the reaction of allylic bromides with thiourea, N-monosubstituted thioureas or thiosemicarbazide. The S-allylic isothiouronium salts substituted with aliphatic groups were found to be the most effective against leukemia cells. These compounds combine high antitumor activity and low toxicity
Treatment of Baylis–Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me2)S+Br−, in MeCN was found to stereoselectively afford (Z)- and (E)-allyl bromides 2. The reaction is rapid at room temperature, high-yielding, and highly stereoselective.
Mild and practical stereoselective synthesis of (Z)- and (E)-allyl bromides from Baylis–Hillman adducts using Appel agents (PPh3/CBr4): a facile synthesis of semiplenamides C and E
Appel agents (PPh3/CBr4) have been utilized for high-yielding stereoselective synthesis of (Z)- and (E)-allyl bromides from Baylis–Hillman adducts at room temperature. The method has been applied for the synthesis of naturallyoccurring bioactive fatty acid amides, semiplenamides C and E.