Total Synthesis of (±)-Alantrypinone by Hetero Diels−Alder Reaction
摘要:
An efficient total synthesis of (+/-)-alantrypinone 4 by hetero Diels-Alder reaction of a novel pyrazine diene 9 with either a functionalized 3-alkylideneoxindole or 3-methyleneoxindole itself is described. The Diels-Alder reactions provide both the desired regiochemistry and exo selectivity. An interesting anionic equilibration between alantrypinone 4 and its epimer 31 or between its ester analogues 23 and 24 has been demonstrated, and a mechanism has been proposed.
Total Synthesis of (±)-Alantrypinone by Hetero Diels−Alder Reaction
摘要:
An efficient total synthesis of (+/-)-alantrypinone 4 by hetero Diels-Alder reaction of a novel pyrazine diene 9 with either a functionalized 3-alkylideneoxindole or 3-methyleneoxindole itself is described. The Diels-Alder reactions provide both the desired regiochemistry and exo selectivity. An interesting anionic equilibration between alantrypinone 4 and its epimer 31 or between its ester analogues 23 and 24 has been demonstrated, and a mechanism has been proposed.
A Concise Total Synthesis of (±)-Alantrypinone by a Novel Hetero-Diels−Alder Reaction
作者:Andrew S. Kende、Junfa Fan、Zecheng Chen
DOI:10.1021/ol030070l
日期:2003.9.1
[reaction: see text] An efficient total synthesis of (+/-)-alantrypinone (1) and its 17-epi isomer (17) has been accomplished employing a novel aza-Diels-Alder reaction as the key step. The reaction sequence comprises 8 steps starting from anthranilic acid and proceeds in 13.5% overall yield. An interesting anionic equilibration between 1 and its epimer 17 has also been discovered.
The gamma-aminobutyric acid (GABA) receptor bears important sites of action for insecticides. Alantrypinone is an insecticidal alkaloid that acts as a selective antagonist for housefly (vs rat) GABA receptors, and is considered to be a lead compound for the development of a safer insecticide. In an attempt to obtain compounds with greater activity, a series of racemic alantrypinone derivatives were systematically synthesized using hetero Diels-Alder reactions, and a total of34 compounds were examined for their ability to inhibit the specific binding of [H-3]4'-ethynyl-4-n-propylbicycloorthobenzoate, a high-affinity non-competitive antagonist, to housefly-head membranes. The assay results showed that (1) there is no significant difference between the potencies of natural (+)-alantrypinone and its synthetic racemate; (2) the amide NHs at the 2- and 18-positions are important for high activity; (3) there is a considerable drop in potency for compounds without an aromatic ring at the 16-position; and (4) a large substituent at the 3-position is detrimental to high activity. (c) 2008 Elsevier Ltd. All rights reserved.
Acid-Catalyzed Aza-Diels−Alder Reactions for the Total Synthesis of (±)-Lapatin B
作者:Dominique Leca、Francesca Gaggini、Jérôme Cassayre、Olivier Loiseleur、Susan N. Pieniazek、Jennifer A. R. Luft、K. N. Houk
DOI:10.1021/jo0705162
日期:2007.5.1
A 5-step total synthesis of microfungal alkaloid (+/-)-lapatin B has been accomplished via a key 2-aza-Diels-Alder reaction. Bronsted acids catalyze the cycloaddition step and provide improved exo selectivity. This synthetic route has been applied to the construction of related spiro-quinazoline structures.