A Facile Route to Polysubstituted<i> N</i>-Benzyl Pyroglutamates
作者:Pei-Pei Sun、Meng-Yang Chang、Michael Y. Chiang、Nein-Chen Chang
DOI:10.1021/ol0344164
日期:2003.5.1
[reaction: see text] Base-induced coupling/cyclizationreactions of alpha-sulfonylacetamide with various ethyl (Z)-2-bromo-2-propenoates have been carried out. The polysubstituted pyroglutamate carbon skeleton, with three contiguous asymmetric centers, was built up in one step. A ring-closure mechanism is proposed for the reactions.
Carbon skeleton of polysubstituted pyroglutamates with three contiguous asymmetric centers was built up in one base-induced coupling/cyclization reaction of α-sulfonylacetamide with 2-bromo-2-propenoates. A simple transformation to 3-substituted prolinols can be easily achieved via reduction and desulfonation. A ring expansion of prolinol has been used as the key step in the formal synthesis of isoguvacine and paroxetine. The one-pot conversion of 3-substituted prolinol to the 3-substituted pyroglutamic acid is also reported.
Base-induced coupling/cyclization stepwise [3+2] annulation of α-sulfonylacetamide with (Z)-2-bromoacrylates yielded polysubstituted pyroglutamates with three contiguous chiral centers with trans–trans orientation in a one-pot synthesis. The pyrrolizidine skeleton was obtained via the ring-closingmetathesis (RCM) method. This facile strategy was used to synthesize psudoheliotridane.
α-Bromo-α,β-unsaturatedesters and α-bromobutenolides reacted with sodium salts of methyl malonamates to afford cyclopropanes, α-methoxycarbonyllactams and 5-amino-4-methoxycarbonyl-2,3-dihydrofurans. The last compounds could be easily converted into α-methoxycarbonyl-γ-lactones. The ratio of these compounds formed is influenced by the structures of both malonamates and unsaturated compounds, especially
The reactions of phenolic reagents with α-bromo Michael acceptors in the K2CO3-acetone system. A stereospecific AdSNE process.
作者:Vittorio Rosnati、Antonio Saba、Aldo Salimbeni
DOI:10.1016/0040-4039(81)80178-5
日期:1981.1
α-bromo Michael acceptors undergo ipso-substitution by phenol or benzenethiol in the K2CO3-acetone system, the reaction originating the (Z) isomers, via a stereospecific AdSNE process.
α-溴Michael受体在K 2 CO 3-丙酮体系中通过苯酚或苯硫酚进行ipso取代,该反应通过立体特异性Ad SN E过程引发(Z)异构体。