81359-37-7Relevant articles and documents
Synthesis of Indolizidine Alkaloids via the Intramolecular Imino Diels-Alder Reaction
Khatri, Nazir A.,Schmitthenner, Hans F.,Shringarpure, Jayant,Weinreb, Steven M.
, p. 6387 - 6393 (1981)
An intramolecular imino Diels-Alder strategy has been developed for total synthesis of the indolizidine alkaloids δ-coniceine (1), tylophorine (2), elaeokanine A (3), and elaeokanine B (4).In all cases, an acyl imine dienophile was generated thermally in situ from a methylol acetate precursor.Diene-methylol acetate 8 has been cyclized via 10 to lactam 11, which was converted to δ-coniceine.Similarly, intermediate methylol acetate 18 was transformed via 19 and 20 to pentacyclic lactam 21, and then to tylophorine.In the syntheses of elaeokanine A and B,a masked diene precursor, in the form of a dihydrothiophene dioxide system, was prepared.Thus, compound 35 was cyclized via intermediate 23b to afford bicyclic lactams 37 and 39 in a 5:4 ratio.These products were subsequently converted to 3 and 4.
Enantioselective synthesis of cyclic amides and amines through Mo-catalyzed asymmetric ring-closing metathesis
Sattely, Elizabeth S.,Alexander Cortez,Moebius, David C.,Schrock, Richard R.,Hoveyda, Amir H.
, p. 8526 - 8533 (2007/10/03)
First, an efficient method for the synthesis of optically enriched N-fused bicyclic structures is reported. Through Mo-catalyzed desymmetrization of readily available achiral polyene substrates, 5,6-, 5,7-, and 5,8-bicyclic amides can be synthesized in up to >98% ee. The effects of catalyst structure, olefin substitution, positioning of Lewis basic functional groups and ring size are examined and discussed in detail. In the second phase of investigations, a catalytic asymmetric method for highly enantioselective (up to 97% ee) synthesis of small- and medium-ring unsaturated cyclic amines is reported; optically enriched products bear a secondary amine or a readily removable Cbz or acetamide unit. Regio- and diastereo-selective functionalizations of olefins within the optically enriched amine products have been carried out. Both catalytic asymmetric methods include transformations that lead to the formation of trisubstituted as well as disubstituted cyclic alkenes. The protocols outlined herein afford various cyclic amines of high optical purity; such products are not easily accessed by alternative protocols and can be used in enantioselective total syntheses of biologically active molecules.
Novel route to fused nitrogen heterocycles by olefin metathesis
Martin, Stephen F.,Liao, Yusheng,Chen, Hui-Ju,Paetzel, Michael,Ramser, Melissa N.
, p. 6005 - 6008 (2007/10/02)
A novel technique for the efficient synthesis of fused nitrogen heterocycles has been developed that features the molybdenum alkylidene-catalyzed metathesis of α,ω-dienes containing a nitrogen atom in the chain linking the two olefinic functional groups. The starting materials may be readily prepared in three steps from succinimide and glutarimide via sequential Mitsunobu alkylation, sodium borohydride reduction, and addition of a vinyl cuprate to an N-acyliminium salt generated in situ.
