Regioselective Alkylations of Cyclic 1,3-Diketonesvia Metalated Dimethylhydrazones
摘要:
Cyclic 1,3- diketones 1 are transformed into their 2,2-dimethylhydrazones 2, which can be alkylated regioselectively at different positions after mono-, di-, tri-, and tetrametalation. Monometalated C-2 unsubstituted hydrazones afford C-2 and N-alkylation, monometalated C-2 substituted hydrazones afford only C-2 alkylation. The regioselectivity of the alkylation of the polymetalated hydrazones follows Hauser's rule according to the sequence: NH- > C-4 Ha > C-5 > C-4 Hb. Hydrolysis of the product hydrazones 3-5 afforded mono-and polyalkylated 1,3- diketones 7 in good yields.
The preparation of 13-methylgon-4-enes and novel 13-polycarbonalkylgon-4-enes by a new total synthesis is described. 13-Alkylgon-4-enes having progestational, anabolic and androgenic activities are prepared by forming a tetracylic gonane structure unsaturated in the 1,3,5(10),9(11) and 14-positions, selectively reducing in the B- and C-rings, and converting the aromatic A-ring compounds so-produced to gon-4-enes by Birch reduction and hydrolysis.
Enantioselective Conia-Ene-Type Cyclizations of Alkynyl Ketones through Cooperative Action of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <i>N</i>-Alkylamine and a Zn-Based Catalyst
作者:Min Cao、Ahmet Yesilcimen、Masayuki Wasa
DOI:10.1021/jacs.8b13757
日期:2019.3.13
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic α-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated
1. A therapeutic composition having progestational activity comprising as active ingredient a 17-aliphatic carboxylic acid ester of 17.alpha.-ethynyl-18-methyl-19-nortestosterone and a pharmaceutical carrier for said compound.
Organocatalytic Sequential One-Pot Double Cascade Asymmetric Synthesis of Wieland−Miescher Ketone Analogues from a Knoevenagel/Hydrogenation/Robinson Annulation Sequence: Scope and Applications of Organocatalytic Biomimetic Reductions
作者:Dhevalapally B. Ramachary、Mamillapalli Kishor
DOI:10.1021/jo070277i
日期:2007.7.1
practical and novel organocatalytic chemo- and enantioselective process for the cascade synthesis of highly substituted 2-alkyl-cyclohexane-1,3-diones and Wieland−Miescher (W−M) ketone analogs is presented via reductive alkylation as a key step. First time, we developed the one-step alkylation of dimedone and 1,3-cyclohexanedione with aldehydes and Hantzsch ester through an organocatalytic reductive alkylation
Catalytic 1,2-Rearrangements: Organocatalyzed Michael/Semi-Pinacol-like Rearrangement Cascade of 1,3-Diones and Nitroolefins
作者:Tsung-Jung Jao、Pavan Sudheer Akula、Bor-Cherng Hong、Gene-Hsiang Lee
DOI:10.1021/acs.orglett.9b03912
日期:2020.1.3
New types of organocatalytic 1,2-rearrangements, which resemble the Smiles-like or semi-pinacol-like rearrangement, of Michael adducts of 1,3-dicarbonyl-2-alkyl compounds and nitroalkenes have been realized. Unlike the well-known conjugate addition, the reaction affords the 1-phenyl-1-nitroalkanes via unprecedentedrearrangement and cascade reactions. Structures of the appropriate products were unambiguously