- Trans-2,5-Disubstituted pyrrolidines: Rapid stereocontrolled access from sulfones
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A direct method for the reliable synthesis of trans-2,5-distributed pyrrolidines from pyroglutamic acid that was conducted at scale and without chromatographic purification of key intermediates was investigated. An analogous reaction involving the partial reduction of succinimides and displacement of the resulting lactol with benzenesulfinic acid yields sulfonyl pyrrolidinones. It was found that a highly diastereoselective and general approach to 2,5-difunctionalized pyrrolidines could be achieved by applying this strategy to the pyroglutamate system. The four step synthesis required no chromatographic purification of intermediates, where the product sulfone was readily purified by recrystallization and the sequence proceeded in 52% overall yield. The results show that such an approach would be of great importance for the preparation of substituted pyrrolidines in natural product systems.
- Moloney, Mark G.,Panchal, Terry,Pike, Richard
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p. 3894 - 3897
(2008/09/18)
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- Convenient synthesis of C-aza-2,3-dideoxynucleosides
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l-Aryl-l,2,3,4-tetradeoxy-l,4-imino-D-pentitols 5 and 9f are easily synthesized from TV-Boc-L-pyroglutamate 1 via a successive procedure involving regioselective ring-opening, recyclization with dehydration, stereoselective reduction, and reduction of the
- Momotake, Atsuya,Togo, Hideo,Yokoyama, Masataka
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p. 1193 - 1200
(2007/10/03)
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- Stereoselective Addition of Grignard-Derived Organocopper Reagents to N-Acyliminium Ions: Synthesis of Enantiopure 5- and 4,5-Substituted Prolinates
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Alkylation of nonracemic N-acyliminium ions derived from proline and 4-substituted prolines has been extended to different types of Grignard-derived organocopper reagents.The reaction proceeds with high yield and stereoselectivity to yield 5-mono- and 4,5-disubstituted prolinates.The stereochemistry is controlled by the formation of a RCu-? complex intermediate between the N-acyliminium ion, the carbonyl group of the ester, and the copper species.
- Collado, Ivan,Ezquerra, Jesus,Pedregal, Concepcion
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p. 5011 - 5015
(2007/10/03)
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