Raymond L. Funk

Total Synthesis of (±)-Communesin F via a Cycloaddition with Indol- 2-one

A concise total synthesis of (±)-communesin F has been completed in 15 linear steps from 4-bromotryptophol in an overall yield of 6.7%. A key step features the cycloaddition of indol-2-one with 3-(2-azidoethyl)-4-bromoindole and facilitates the rapid construction of the lower aminal-containing tetracyclic core of the natural product.

Total Synthesis of (−)-Nakadomarin A

A concise diastereoselective total synthesis of (-)-nakadomarin A has been completed in 21 steps from D-pyroglutamic acid. Key steps include an enecarbamate Michael addition/furan-N-acyliminium ion cascade cyclization to provide the tetracyclic core and ring-closing alkyne and alkene metatheses to construct the fifteen- and eight-membered azacycles, respectively.

Total Synthesis of (±)-Cortistatin J from Furan

A concise, diastereoselective total synthesis of (±)-cortistatin J has been completed in 20 steps from furan. Key steps include an intramolecular [4 + 3] cyclization of a disubstituted furan with a (Z)-2-(trialkylsilyloxy)-2-enal to construct the tetracyclic core and a (Z)-vinylsilane/iminium ion cyclization to form the A ring.

Preparation of 2-Alkyl- and 2-Acylpropenals from 5-(Trifluoromethanesulfonyloxy)-4H-1,3-dioxin: A Versatile Acrolein α-Cation Synthon

Abstract 5-(Trifluoromethanesulfonyloxy)-4 H -1,3-dioxin ( 3 ) participates in a variety of nucleophilic substitution reactions with cuprate reagents or in palladium catalyzed cross-coupling reactions to provide 5-substituted-4 H -1,3-dioxins 5 . Upon thermolysis, these compounds undergo facile retrocycloaddition reactions to generate the corresponding 2-substituted acroleins which, if necessary, can be trapped in situ with dienes or heterodienophiles. In particular, the heretofore unknown 2-acylacroleins can be generated using this methodology and trapped with enol ethers to afford 5-acyl-3,4-dihydro-2 H -pyrans ( 6g , h ), a substructural unit common to many natural products.

Stereoselective preparation of vinyl sulfones by protodesilylation of allyl silanes

Abstract Allyl sulfones can be conjugated to furnish vinyl sulfones via allyl silane intermediates. The stereoselectivity observed in the protodesilylation step provides a new method for stereoselective preparation of (E)-di-and trisubstituted vinyl sulfones.

C(1)-Substituted menthol derivatives: Self-removing chiral auxiliaries for asymmetric conjugate additions to cycloalkenones

Abstract C(1)-substituted (−)-menthone derivatives 3 were prepared by the stereoselective addition of the alkenyllithium reagents 9 to menthone ( 8 ) and subsequent acid catalyzed hydrolysis of the dioxolane protecting groups. Conjugate addition of cuprate reagents to enones 3a,b followed by a methanol quench directly gave the β-alkylcycloalkanones 7 via retro-aldol reactions in 80–91% ee.