Palladium-promoted Cyclization Research Articles

ChemInform Abstract: Total Synthesis of the Antitumor Marine Sponge Alkaloid Agelastatin A.

The first total synthesis of the cytotoxic marine metabolite agelastatin A (1) has been achieved in about 14 steps performed in 12 operations in approximately 7% overall yield starting from cyclopentadiene. Hetero Diels−Alder cycloaddition of cyclopentadiene with N-sulfinyl methyl carbamate (7) afforded cycloadduct 8, which without purification was converted to allylic sulfoxide 9 and then by a [2,3]-sigmatropic rearrangement into bicyclic oxazolidinone 11. The C-5a nitrogen was introduced into the oxazolidinone Boc derivative 16 by a Sharpless/Kresze allylic amination with SES sulfodiimide 12c. Palladium-promoted cyclization of 2-acyl pyrroles 20 and 21 via a π-allylpalladium intermediate 22 led to ABC-tricycles 23 and 24, respectively. A hydroxyl urea D-ring model system was constructed by hydroborating 24, leading eventually to keto amide 31 and then to tetracycle 33. A modified strategy was developed for synthesis of the pivotal tricyclic ketone 58, involving as key steps a chemoselective hydrolysis o...

Total Synthesis of the Natural Carbazoles Murrayanine and Murrayafoline A, Based on the Regioselective Diels?Alder Addition of exo-2-Oxazolidinone Dienes.

A new synthesis of the natural carbazoles Murrayanine (1) and Murrayafoline A (3) is described. The key step in the synthetic route involved the regioselective cycloaddition of the diene 4,5-dimethylene-3-phenyl-1,3-oxazolidin-2-one (4) to acrolein (6) catalyzed by Lewis acids at low temperature. Direct aromatization of the substituted cyclohexene moiety of adduct 7, and further hydrolysis of the 2-oxazolidinone ring, proved to be a more efficient strategy than the opposite synthetic sequence for the preparation of the corresponding arylphenylamines 14 and 18. Palladium-promoted cyclization of the latter furnished the desired carbazoles 1 and 3 in high overall yields.

Total Synthesis of the Natural Carbazoles Murrayanine and Murrayafoline A, Based on the Regioselective Diels-Alder Addition ofexo-2-Oxazolidinone Dienes

A new synthesis of the natural carbazoles Murrayanine (1) and Murrayafoline A (3) is described. The key step in the synthetic route involved the regioselective cycloaddition of the diene 4,5-dimethylene-3-phenyl-1,3-oxazolidin-2-one (4) to acrolein (6) catalyzed by Lewis acids at low temperature. Direct aromatization of the substituted cyclohexene moiety of adduct 7, and further hydrolysis of the 2-oxazolidinone ring, proved to be a more efficient strategy than the opposite synthetic sequence for the preparation of the corresponding arylphenylamines 14 and 18. Palladium-promoted cyclization of the latter furnished the desired carbazoles 1 and 3 in high overall yields.

ChemInform Abstract: Palladium-Promoted Cyclization Reactions in the Synthesis of Biologically Active Natural Products

ChemInform Abstract: Palladium-Promoted Cyclization Reactions in the Synthesis of Biologically Active Natural Products

Total Synthesis of the Antitumor Marine Sponge Alkaloid Agelastatin A

The first total synthesis of the cytotoxic marine metabolite agelastatin A (1) has been achieved in about 14 steps performed in 12 operations in approximately 7% overall yield starting from cyclopentadiene. Hetero Diels−Alder cycloaddition of cyclopentadiene with N-sulfinyl methyl carbamate (7) afforded cycloadduct 8, which without purification was converted to allylic sulfoxide 9 and then by a [2,3]-sigmatropic rearrangement into bicyclic oxazolidinone 11. The C-5a nitrogen was introduced into the oxazolidinone Boc derivative 16 by a Sharpless/Kresze allylic amination with SES sulfodiimide 12c. Palladium-promoted cyclization of 2-acyl pyrroles 20 and 21 via a π-allylpalladium intermediate 22 led to ABC-tricycles 23 and 24, respectively. A hydroxyl urea D-ring model system was constructed by hydroborating 24, leading eventually to keto amide 31 and then to tetracycle 33. A modified strategy was developed for synthesis of the pivotal tricyclic ketone 58, involving as key steps a chemoselective hydrolysis o...

パラジウム錯体による環化反応を利用した生理活性天然物の合成研究

The use of palladium complexes as reagents for the synthesis of biologically active natural products has been under development for at least the past three decades, and many elegant total syntheses of structurally complicated natural products, possessing pharmacologically important properties, have been realized employing Heck reaction, cycloisomerization process, and allylic alkylation reaction. In our recent contribution to this area, we would like to describe total syntheses of aphidicolin (diterpene), pumiliotoxin C (alkaloid), methyl pederate (left segment of mycalamides), hirsutene (sesquiterpene), stemodin (diterpene), and methyl atis-16-en-19-oate (diterpene) using palladium-promoted cyclization as key step.Although the palladium-promoted cycloalkenylation reaction of an olefinic silyl enol ether is a powerful strategy for construction of polycyclic system, relatively little is known about successful application of the above reaction to biologically active natural product syntheses. Herein we report the development of novel palladium-catalyzed cycloalkenylation reaction of cross-conjugated silyl enol ethers and its application to a tetracyclic diterpene synthesis.

New applications of organopalladium compounds in organic synthesis

Abstract

Synthesis of butenolides via palladium-promoted cyclization of acyclic allylic esters of chloromercurioacetic acid

Acyclic allylic esters of chloromercurioacetic acid react with Li 2PdCl 4 to afford good yields of butenolides.

ChemInform Abstract: Synthesis of Benzofurans (II) via Palladium‐Promoted Cyclization of ortho‐Substituted Aryl Allyl Ethers (I), (III), (IV).

ChemInformVolume 20, Issue 12 Heterocyclic Compounds ChemInform Abstract: Synthesis of Benzofurans (II) via Palladium-Promoted Cyclization of ortho-Substituted Aryl Allyl Ethers (I), (III), (IV). R. C. LAROCK, R. C. LAROCK Dep. Chem., Iowa State Univ., Ames, IA 50011, USASearch for more papers by this authorD. E. STINN, D. E. STINN Dep. Chem., Iowa State Univ., Ames, IA 50011, USASearch for more papers by this author R. C. LAROCK, R. C. LAROCK Dep. Chem., Iowa State Univ., Ames, IA 50011, USASearch for more papers by this authorD. E. STINN, D. E. STINN Dep. Chem., Iowa State Univ., Ames, IA 50011, USASearch for more papers by this author First published: March 21, 1989 https://doi.org/10.1002/chin.198912173AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue12March 21, 1989 RelatedInformation

Synthesis of unsaturated bicyclic lactones and acetals via palladium-promoted cyclization of cyclic allylic alcohols

Unsaturated bicyclic lactones are readily prepared by converting cyclic allylic alcohols to the corresponding α-chloromercurio acetate esters and reacting them with Li 2PdCl 4. The corresponding acetals can be synthesized directly by reaction of the allylic alcohols with ethyl vinyl ether and Pd(OAc) 2.

Synthesis of benzofurans via palladium-promoted cyclization of ortho-substituted aryl allyl ethers

o -Iodo- or (chloromercurio)aryl allyl ethers undergo facile palladium-promoted cyclization to benzofurans.

Palladium-promoted cyclization reactions of aminoalkenes

The trifluoromethanesulphonate salts of the aminoalkenes CH 2CH(CH 2) 3-NH 2, its 2-methyl, 2,2-dimethyl and N-iso-propyl-derivatives, and CH 2CH-(CH 2) 4NH 2 cyclize in the presence of [PdCl 2(PhCN) 2] and a nitrogen base to produce the corresponding C- or N-substituted 2-methylpyrrolidines and 2-methylpiperidine. E-CH 3CHCH(CH 2) 3NH 2 produces 2-ethylpyrrolidine and a small amount of 2-methylpiperidine. The regio-selectivity of these reactions differs from that observed for the cyclization of the same substrates promoted by [PtCl 4] 2-: (1) the palladium reaction with 2-methylpent-4-enylamine produces ca. a 4 : 6 ratio of cis- and trans-2, 4-dimethylpyrrolidine while with platinum the converse is true; (2) there is a more marked tendency for attack of the amine at the more substituted alkene carbon atom in the palladium than in the platinum reactions.

Palladium-promoted cyclization of diphenyl ether, diphenylamine, and related compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPalladium-promoted cyclization of diphenyl ether, diphenylamine, and related compoundsBjorn Akermark, Lennart Eberson, Ernst Jonsson, and Egon PetterssonCite this: J. Org. Chem. 1975, 40, 9, 1365–1367Publication Date (Print):May 1, 1975Publication History Published online1 May 2002Published inissue 1 May 1975https://doi.org/10.1021/jo00897a048RIGHTS & PERMISSIONSArticle Views1931Altmetric-Citations212LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (386 KB) Get e-Alerts Get e-Alerts