Steven R. Angle

Stereoselective synthesis of substituted pipecolic acids

Abstract The stereoselective synthesis of Δ 4,5 -pipecolic acid derivatives is described. The key step in the sequence is a [3,3] sigmatropic rearrangement.

A stereoselective formal synthesis of (±)-(γ)-lycorane

Abstract Compound 11 , a common intermediate in several syntheses of (±)-γ-lycorane, was prepared, from commercially available N -triisopropylsilyl pyrrole, in 13 steps and overall 34% yield. The key step of the synthesis involved the diastereoselective hydrogenation of a substituted pyrrole ring.

A general route for the synthesis of enantiopure indolizidine alkaloids from α-amino acids. Total synthesis of (+)-monomorine

Abstract The ant trail pheromone (+)-Monomorine was synthesized in 9 steps from N-t -BOC- L -alanine ethyl ester. The key step of the synthesis is the conformationally restricted Claisen rearrangement of lactone 9 to pipecolic ester 11 .

Quinone methide initiated cyclization reactions: Studies toward the synthesis of (+)-pancratistatin

Abstract The synthesis of highly functionalized cyclohexenone 15 , a possible precursor for (+)-pancratistatin, was accomplished in 15 steps (10% yield) from aldehyde 4 via a quinone methide initiated cyclization reaction.

An Approach to the Narciclasine Alkaloids via a Quinone Methide Initiated Cyclization Reaction

The stereoselective synthesis of a possible intermediate for the synthesis of the narciclasine alkaloids from D-glucose is described. The key step of the sequence is a quinone methide initiated cyclization reaction.

Para-quinone methide initiated intramolecular electrophilic substitution reactions

Abstract A study on the reactivity of para -quinone methides in intramolecular cyclization reactions is presented. The para -quinone methides were isolated and completely characterized prior to cyclization. A furan, a pyrrole and a mono-alkyl substituted benzene were used as cyclization terminators.

Stereoselective synthesis of 4-aryl-2-(benzyloxy)carbonyl-3-hydroxy tetrahydrofurans from aryl epoxides

Abstract The stereoselective synthesis of 4-aryl substituted tetrahydrofurans from benzyl diazoacetate and aryl epoxides is described.

Formal [3+3]- and [3+2]-cycloadditions of allylsilanes with benzylic cations

Abstract Allylsilanes serve as three-carbon dipole equivalents for the formation of tetrahydronaphthalenes via Lewis-acid promoted formal [3+3]-cycloadditions with benzylic cations. A competing [3+2]-pathway resulted in the formation of dihydro(1 H )indenes. Both quinone methides and benzylic alcohols were used as precursors to the benzylic cations.

Synthesis of 1,2-dihydronaphthalenes and spiro[4.5]-deca-3,6,9-trien-8-ones from benzylic alcohols

Abstract The synthesis of 1,2-dihydronaphthalenes and spiro[4.5]decatrienones via reaction of an allenylsilane and a benzylic cation is reported.

Cationic cyclization reactions initiated by stabilized benzyl cations

Abstract The in situ generation of stabilized benzyl cations and their subsequent use in cyclization reactions with a monosubstituted benzene, a furan and a β-keto ester terminators is described.