A 10-step asymmetric synthesis of 9-epi-sessilifoliamide J (20), together with sessilifoliamide J (6), has been accomplished from the key chiral building block 11 via a threo-selective vinylogous Mannich reaction and a Ley oxidation-SmI(2)-mediated coupling lactonization. The absolute configuration of the natural sessilifoliamide J was established.

The halo-assisted intramolecular addition of silyl enol ethers with in situ activated lactams yielded (hydroxylated) 1-halo-8-azabicyclo[3,2,1]octane and 1-halo-9-azabicyclo[3,3,1]nonane ring systems, which provided an easy enantioselective access to 6β-silyloxytropane-3-one, 3α,6β-dihydroxytropane, and pervilleine B. The absolute configuration of the natural (-)-pervilleine B was determined to be 1R,3R,5S,6R.

Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration (C-9/C-9a). In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI 2 -mediated reductive coupling of ketone 6 and β-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an α-directing (chelation) group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate afforded spiro-α-methylene-γ-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyrrolidine moieties. In addition, on the basis of our previous work, the total synthesis of (−)-9-epi-11-demethylsessilifoliamide J (11), and an improved synthesis of (−)-9,11-di-epi-sessilifoliamide J (9) were accomplished.

We describe efficient and flexible enantioselective syntheses of the active enantiomers of the pheromones of pine sawflies, including the species Diprion jingyuanensis, their homologs and, stereoisomers, as well as those identified from the Chinese species Diprion jingyuanensis, i.e., 126. A total of 48 compounds, including acetates 78101 and propanoates 102125, have been synthesized. Our general approach towards these compounds originated from the commercially available chirons diethyl (S)- and (R)-malates, as well as ethyl (R)-3-hydroxybutanoate. The Seebach asymmetric methylation was employed in a key step to control additional configuration.National Basic Research Program (973 Program) of China [2010CB833200]; NSF of China [20832005, 21072160]; Natural Science Foundation of Fujian Province of China [2011J01054

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