Preparation and Double Michael Addition Reactions of a Synthetic Equivalent of the Nazarov Reagent

A synthetic equivalent of the Nazarov reagent, the silyl derivative <b>2</b>, able to undergo base-catalyzed double Michael addition reactions with α,β-unsaturated carbonyl compounds has been developed. The new reagent satisfactorily reacts with unsaturated indolo[2,3-<i>a</i>]quinolizidine lactams to give pentacyclic yohimbinone-type derivatives

Preparation and Double Michael Addition Reactions of a Synthetic Equivalent of the Nazarov Reagent

A synthetic equivalent of the Nazarov reagent, the silyl derivative <b>2</b>, able to undergo base-catalyzed double Michael addition reactions with α,β-unsaturated carbonyl compounds has been developed. The new reagent satisfactorily reacts with unsaturated indolo[2,3-<i>a</i>]quinolizidine lactams to give pentacyclic yohimbinone-type derivatives

Stereoselective Total Synthesis of the Putative Structure of Nitraraine

After the structure originally proposed for nitraraine was shown to be incorrect by total synthesis, the alternative structure <b>5</b> was recently suggested for the alkaloid on biosynthetic grounds and by comparison with the ¹H NMR data of tangutorine. The unambiguous synthesis of <b>5</b> is reported from tryptophanol and ketodiester <b>6</b>, via oxazoloquinolone lactam <b>7</b>. However, the melting point and ¹H NMR data of <b>5</b> did not match those reported for the natural product

Model Studies on the Synthesis of Madangamine Alkaloids. Assembly of the Macrocyclic Rings

Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C–E, the all-<i>cis</i>-triunsaturated 15-membered D ring of madangamine A, and the (<i>Z</i>,<i>Z</i>)-unsaturated 11-membered E ring common to madangamines A–E, has been studied

Enantioselective Synthesis of Spiro[indolizidine-1,3\u2032-oxindoles]

A three-step procedure for the enantioselective synthesis of spiro[indolizidine-1,3'-oxindoles], consisting of a stereoselective cyclocondensation reaction between (S)-tryptophanol and a prochiral or racemic 5-oxoester, bromination of the resulting oxazolopiperidone lactam, and a final stereoselective spirocyclization, is reported

Enantioselective Synthesis of Spiro[indolizidine-1,3′-oxindoles]

A three-step procedure for the enantioselective synthesis of spiro­[indolizidine-1,3′-oxindoles], consisting of a stereoselective cyclocondensation reaction between (<i>S</i>)-tryptophanol and a prochiral or racemic δ-oxoester, bromination of the resulting oxazolopiperidone lactam, and a final stereoselective spirocyclization, is reported