Communication

October 23, 2004

Anodic Coupling Reactions: the Use of N,O-Ketene Acetal Coupling Partners

Yung-tzung Huang and Kevin D. Moeller
Org. Lett., 2004, 6 (23), pp 4199–4202

Intramolecular anodic olefin coupling reactions utilizing N,O-ketene acetals have been studied. Coupling reactions with both enol ether and allylsilane terminating groups were examined. The reactions involving the coupling of the N,O-ketene acetals with allylsilane groups were found to be much more efficient than corresponding reactions utilizing dithioketene acetal groups and allylsilanes. The reactions were also more efficient than the intramolecular coupling reactions between enol ethers and allylsilanes studied earlier.

 

April 28, 2004

Building Addressable Libraries: The Use of Electrochemistry for Generating Reactive Pd(II) Reagents at Preselected Sites on a Chip

Eden Tesfu, Karl Maurer, Steven R. Ragsdale, and Kevin D. Moeller
J. Am. Chem. Soc., 2004, 126 (20), 6212–6213

A Pd(II) reagent has been generated at preselected sites on an electrochemically addressable chip. The reagent was used to effect the Wacker oxidation of an olefin substrate bound to the chip near the electrode. The use of ethyl vinyl ether in the solution above the chip effectively kept the Pd(II) reagent generated at the preselected electrode from migrating to neighboring electrodes and initiating Wacker oxidations at unwanted sites on the chip.

 

August 15, 2003

Building Functionalized Peptidomimetics: New Electroauxiliaries and the Use of a Chemical Oxidant for Introducing N-Acyliminium Ions into Peptides

Haizhou Sun and Kevin D. Moeller
Org. Lett., 2003, 5 (18), pp 3189–3192

The removal of electroauxiliaries from peptide substrates with chemical oxidants has been examined as a method for inserting N-acyliminium ions into the peptides. To this end, it was found that both 4-methoxyphenyldimethylsilyl and 2,4-dimethoxyphenyldimethylsilyl electroauxiliaries were readily cleaved with the use of ceric ammonium nitrate. Of the two groups, the 2,4-dimethoxyphenyldimethylsilyl electroauxiliary was the most labile under the oxidative conditions. The oxidation reactions were shown to be compatible with the use of a solid-phase substrate.

 

December 5, 2002

Anodic Cyclization Reactions: the Total Synthesis of Alliacol A

John Mihelcic and Kevin D. Moeller
J. Am. Chem. Soc., 2003, 125 (1), pp 36–37

An anodic cyclization−Friedel Crafts alkylation strategy has been used to rapidly assemble the core ring system of alliacol A and to complete a formal total synthesis of the natural product. The anodic cyclization reaction was used to effect the coupling of a nucleophilic furan ring to the normally nucleophilic carbon of a silyl enol ether. The substrate for this initial cyclization reaction contained all of the carbons needed for completing the total synthesis. The electrolysis proceeded in high yield and could be accomplished with the use of a 6 V lantern battery.

 

October 4, 2002

Anodic Olefin Coupling Reactions Involving Ketene Dithioacetals: Evidence for a ‘Radical-type’ Cyclization

Yongmao Sun and Kevin D. Moeller
Tetrahedron Letters, 2002, 43(40), 7159-7161
 

A series of anodic coupling reactions between ketene dithioacetal groups and enol ethers have been studied in order to probe why some of the cyclizations are successful while other closely related attempts fail. It has been found that the success of the cyclization reactions strongly depends on the location of substituents on the olefins. The reactions are highly sensitive to substituents on the terminating olefin but not to substituents on the initial radical cation. This behavior is consistent with what has been observed previously with radical cyclization reactions.

The success of anodic couplings between ketene dithioacetals and enol ethers that form quaternary centers show the same dependence on substituent location that is observed for radical cyclization reactions.

 

August 31, 2001

Anodic Oxidation Reactions: the Total Synthesis of (+)-Nemorensic Acid

Bin Liu and Kevin D Moeller
Tetrahedron Letters, 2001, 42(41), 7163-7165
 

The anodic coupling of an enol ether to an oxygen nucleophile has been used as a key step in the total synthesis of (+)-nemorensic acid. The anodic cyclization reaction allows for a reversal in the way the tetrahydrofuran ring of the natural product is normally assembled and thus enables construction of the ring in a highly stereoselective fashion.

The anodic coupling of a ketene dithioacetal and an oxygen nucleophile has been used as the key step in an 11-step synthesis of (+)-nemorensic acid.

 

August 28, 2001

Anodic Cyclization Reactions: Reversing the Polarity of Ketene Dithioacetal Groups

Yongmao Sun, Bin Liu, Jeff Kao, D. Andre’ d’Avignon, and Kevin D. Moeller
Org. Lett., 2001, 3 (11), 1729–1732

Intramolecular coupling reactions of ketene dithioacetal groups with enol ether and alcohol nucleophiles have been studied. The reactions were initiated by an anodic oxidation of the ketene dithioacetal and proved to be compatible with the formation of five- or six-member rings, as well as the stereoselective generation of quaternary carbons.

 

July 27, 2001

Anodic Coupling Reactions: Probing the Stereochemistry of Tetrahydrofuran Formation. A Short, Convenient Synthesis of Linalool Oxide

Shengquan Duan and Kevin D. Moeller
Org. Lett., 2001, 3 (17), 2685–2688

Intramolecular coupling reactions between enol ether radical cations and oxygen nucleophiles are primarily governed by stereoelectronics. By taking advantage of this observation, a tetrahydrofuran building block for use in constructing (+)-linalool oxide and rotundisine has been synthesized in four steps from a commercially available starting material. The synthesis of (+)-linalool oxide has been completed.

 

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