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A concise enantio- and stereocontrolled synthesis of (+)-lycoperdic acid is presented. The stereochemical control is based on iminium-catalyzed Mukaiyama–Michael reaction and enamine-catalyzed organocatalytic α-chlorination steps. The amino group was introduced by azide displacement, affording the final stereochemistry of (+)-lycoperdic acid. Penultimate hydrogenation and hydrolysis afforded pure (+)-lycoperdic acid in seven steps from a known silyloxyfuran. peerReviewed

Enantioselective iminium-catalyzed reactions with acrolein and methacrolein are rare. A catalytic enantioselective Mukaiyama-Michael reaction that readily accepts acrolein or methacrolein as substrates, affording the products in good yields and 91-97% ee, is presented. As an application of the methodology, an enantioselective route to the key C17-C28 segment of the pectenotoxin using the Mukaiyama-Michael reaction as the key step is described.

A highly stereocontrolled and efficient synthesis for a fully functionalized C 10-C 22 fragment of pectenotoxin 2 is described using a convergent sequence involving a stereoselective methylation of beta-hydroxyketone as a key step.

[structure: see text] A concise synthesis of both AB ring spiroisomers of the pectenotoxins is described. The nonanomeric AB spiroketal ring system of the pectenotoxins-1, -2, -3, and -6 is formed under very mild, kinetic spiroketalization conditions, along with the anomeric isomer. Only catalytic asymmetric transformations were used as the source of chirality in the synthesis route.

A convergent synthesis of the CDE and CDEF ring systems of pectenotoxin-2 from C and F ring precursors is described.

An efficient urea-enhanced thiourea catalyst enables the enantioselective Mannich reaction between β-keto esters and N-Boc-protected imines under mild conditions and minimal catalyst loading (1–3 mol %). Aliphatic and aromatic substituents are tolerated on both reaction partners, affording the products in good enantiomeric purity. The corresponding β-amino ketones can readily be accessed via decarboxylation without loss of enantiomeric purity.