A new and efficient one-pot strategy combining catalyst-free synthesis and iodinecatalysis has been developed for the synthesis of dihydrofuropyrimidines and spirodihydrofuropyrimidine pyrazolones. This approach affords products in moderate to high yields (up to 96%) with excellent diastereoselectivities (up to >25 : 1 dr). The reaction is simple to carry out and is metal-free.
The Regiocontrollable Enantioselective Synthesis of Chiral Trifluoromethyl-Containing Spiro-Pyrrolidine-Pyrazolone Compounds via Amino-Regulated 1,3-Proton Migration Reaction
as catalyst, the 1,3-dipolar cycloaddition of α,β-unsaturated pyrazolone with diethyl2-((2,2,2-trifluoroethyl)imino) malonate offered adducts in excellent yields, dr, and ee. While the cyclohexanediamine-derived squaramide was employed, the reaction afforded a series of structure isomers through a switched umpolung reaction.
描述了含CF 3的螺-吡咯烷-吡唑啉酮化合物的氨基控制区域发散不对称合成。以生物碱衍生的方酸酰胺为催化剂,α,β-不饱和吡唑啉酮与 2-((2,2,2-三氟乙基)亚氨基)丙二酸二乙酯的 1,3-偶极环加成反应以优异的收率、dr 和 ee 提供加合物。虽然使用了环己二胺衍生的方酸酰胺,但该反应通过转换的 umpolung 反应提供了一系列结构异构体。
Enantioselective aminocatalytic synthesis of tetrahydropyrano[2,3-c]pyrazoles via a domino Michael-hemiacetalization reaction with alkylidene pyrazolones
作者:Rajendra Maity、Subhas Chandra Pan
DOI:10.1039/c7ob02170d
日期:——
An enantioselectiveorganocatalytic domino Michael-hemiacetalization reaction between alkylidene pyrazolones and cyclic ketones/pentanal has been revealed. The fused tetrahydropyranopyrazole products having three contiguous stereocentres were obtained with perfect diastereoselectivities and in moderate to good yields with good to high enantioselectivities. Also, few synthetic transformations of the
Squaramide-catalysed asymmetric Friedel–Crafts alkylation of naphthol and unsaturated pyrazolones
作者:Ran Wei、Li Gao、Gaihui Li、Li Tang、Guoshun Zhang、Feilang Zheng、Heng Song、Qingshan Li、Shurong Ban
DOI:10.1039/d1ob00347j
日期:——
The first method for highly efficient asymmetric Michael-type Friedel–Craftsalkylation of naphthol and unsaturated pyrazolones has been accomplished under mild reaction conditions. In the presence of the chiral squaramide catalyst, a wide range of substrates are tolerated in excellent yields (up to 99%) with reasonable enantioselectivities (up to 96% ee).
在温和的反应条件下完成了萘酚和不饱和吡唑啉酮类高效不对称 Michael 型 Friedel-Crafts 烷基化的第一种方法。在手性方酸酰胺催化剂的存在下,可以以优异的收率(高达 99%)和合理的对映选择性(高达 96% ee)耐受各种底物。
Enantio‐ and Diastereoselective Synthesis of β<i>‐</i>Aryl<i>‐</i>β<i>‐</i>pyrazolyl α‐Amino Acid Esters via Copper‐Catalyzed Reaction of Azomethine Ylides with Benzylidenepyrazolones
stereoselective synthesis of unnatural chiral β‐aryl‐β‐pyrazolyl α‐amino acidesters via copper‐catalyzed addition reactions of azomethine ylides with benzylidenepyrazolones bearing two contiguous stereogenic centers was developed. A 1H‐pyrazol‐5‐ol was introduced by the aromatization of 3H‐pyrazol‐3‐one in the reaction. The transformation operated at room temperature and afforded β‐1H‐pyrazol‐5‐ol‐α‐amino