Communication

November 5, 1999

The Synthesis of Bicyclic Lactam Based His-Pro Building Blocks: the Effect of Substituent Polarity on an Intramolecular Bond Migration

Wenhua Chu and Kevin D. Moeller

Tetrahedron Lett., 1999, 40(45), 7939-7943

A strategy for constructing bicyclic lactam amino acid building blocks with imidazole sidechains is reported. The synthetic route described utilizes an electrochemical amide oxidation to functionalize a proline derivative, and then a sequential cyclization-rearrangement strategy to construct a substituted six-membered ring lactam. Alternatively, the seven-membered ring lactams were obtained without rearrangement when electron withdrawing groups were present beta to the amide carbonyl.

 

July 18, 1996

Intramolecular Anodic Olefin Coupling Reactions: the Use of an Allylic Alkoxy Group for Controlling Relative Stereochemistry

Dean A. Frey, Jeffery A. Marx and Kevin D. Moeller

Electrochimica Acta, 1997, 42(13-14), 1967-1970

The study of intramolecular anodic olefin coupling reactions arising from diene substrates having an allylic alkoxy group have been studied. In all cases, the coupling reactions proceeded smoothly without elimination of the allylic alkoxy group. In addition, the reactions were found to afford five-membered ring products in a diastereoselective fashion. Substrates having both cis- and trans-disubstituted allyl silane olefin participants led to different ratios of products indicating that the cyclization reactions were under kinetic control.

 

May 2, 1994

Intramolecular Anodic Olefin Coupling Reactions: Initial Studies Concerning the Use of Electron-rich Aryl Rings

Kevin D. Moeller and Dallas G. New

Tetrahedron Lett., 1994, 35(18), 2857-2860

Intramolecular anodic olefin coupling reactions involving electron-rich aryl rings were examined and shown to afford fused bicyclic products. When alkoxysubstituted phenyl rings were used, the reactions benefited from the use of either controlled potential electrolysis conditions or a vinyl sulfide initiating group. Coupling reactions involving heteroatomic aryl rings also led to good yields of cyclized product.

 

February 28, 1991

Anodic amide oxidations in the presence of electron-rich phenyl rings: evidence for an intramolecular electron-transfer mechanism

Kevin D. Moeller, Po W. Wang, Sharif Tarazi, Mohammad R. Marzabadi, Poh Lee Wong

J. Org. Chem., 1991, 56(3), 1058–1067

The anodic oxidationsof amides in the presence of mono-, di-, and trialkoxyphenyl rings were examined. Although literature reduction potentials suggest that these oxidations would lead to either selective aromatic ring oxidation or mixtures, the chemoselectivity of the reactions was found to be dependent on the substitution pattern of the phenyl ring. For example, the anodic oxidations of ((3-methoxyphenyl)acetyl)pyrrolidine, ((2-methoxy-phenyl)acetyl)pyrrolidine, ((3-methoxy-4-(pivaloyloxy)phenyl)acetyl)pyrrolidine, and ((3,5-dimethoxy-4-(piva-1oyloxy)phenyl)acetyl)pyrrolidine all led to selective methoxylation of the pprolidine ring. The anodic oxidations and of (4-methoxypheny1)acetyl)pyrrolidine ((3,4-dimethoxyphenyl)acetyl)pyrrolidineled to selective methoxylation of the benzylic carbon. Mechanistic studies indicate that both amide and aryl oxidation processes compete under the reaction conditions, but that intramolecular electron transfer leads to the selective formation of products. Evidence for this mechanism was obtained by examining the cyclic voltammogram of ((3-methoxypheny1)-acetyl)pyrrolidine, competition studies, and the preparative electrolysis of (4-methoxypheny1)dimethyl-acety1)pyrrolidine. The methoxylated amides were cyclized to form tricyclic amides using titanium tetrachloride.

 

November 18, 1988

Electrochemical amide oxidations in the presence of monomethoxylated phenyl rings. An unexpected relationship between the chemoselectivity of the oxidation and the location of the methoxy substituent

Kevin D. Moeller, Sharif Tarazi, Mohammad R Marzabadi

Tetrahedron Lett., 1989, 30(10), 1213-1216

The chemoselectivity of electrochemical amide oxidations in the presence of monomethoxylated phenyl rings was examined. Oxidation of (3-methoxyphenyl)acylpyrrolidine led to exclusive formation of the desired amide oxidation products, while oxidation of the 4-methoxyphenyl isomer led to exclusive formation of aromatic ring oxidation products.

The chemoselectivity of electrochemical amide oxidations in the presence of monomethoxy phenyl rings was found to be completely dependent on the position of the methoxy substituent.

 

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