Intramolecular Diels-Alder (IMDA) Studies toward the Synthesis of Australifungin. Stereocontrol in the Acetate Aldol Reaction of β,β'-Branched Aldehydes

Studies of australifungin illustrate an enantiocontrolled synthesis of the trans-decalin core 28 via an intramolecular [4π + 2π] cycloaddition. This strategy utilizes the nitroalkene dienophile of 27 as a surrogate ketene equivalent. Stereocontrol at C-2 is critically important for an effective intramolecular Diels-Alder (IMDA) process. Our studies report high asymmetric induction using a nonracemic Duthaler titanium enolate in the acetate aldol reaction with β,β'-branched aldehyde 13 to introduce the required C-2 chirality.

Characterization of a Behaviorally Active, Gender-Specific Volatile Compound from the Male Asparagus Fly Plioreocepta poeciloptera

Adult male asparagus flies exhibit typical calling behaviors (suggestive of pheromone production) during which they emit a single volatile compound that was identified as isopropyl (S)-5-hydroxyhexanoate. In laboratory bioassays, synthetic samples elicited an arrestant response in females, but did not appear to attract females. On the other hand, the synthetic material attracted conspecific males in olfactometer bioassays.

The stereocontrolled total synthesis of altohyrtin A/spongistatin 1: the CD-spiroacetal segment

Stereocontrolled syntheses of the C16-C28 CD-spiroacetal subunit of altohyrtin A/spongistatin 1 , relying on kinetic and thermodynamic control of the spiroacetal formation, are described. The kinetic control approach resulted in a slight preference (60 : 40) for the desired spiroacetal isomer. The thermodynamic approach allowed ready access to the desired spiroacetal by acid-promoted equilibration, chromatographic separation of the C23 epimers and resubjection of the undesired isomer to the equilibration conditions. This scalable synthetic sequence provided multi-gram quantities of , thus enabling the successful completion of the total synthesis of altohyrtin A/spongistatin 1, as reported in Part 4 of this series.

Enantioselective synthesis of syn- and anti-1,3-diols via allyltitanation of unprotected beta-hydroxyaldehydes

[reaction: see text] syn or anti-1,3-Diols units were synthesized with excellent diastereomeric excess from unprotected chiral beta-hydroxyaldehydes by using an enantioselective allyltitanation.