- Cleavage of activated cyclic amines: Unprecedented approach toward 2-substituted cyclobutanones
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(Chemical Equation Presented) We report, for the first time, ring opening of activated four- to six-membered cyclic amines followed by an intramolecular expansion of cyclopropanol to cyclobutanone via carbocation intermediate. In the case of a N-tosylazir
- Baktharaman, Sivaraj,Selvakumar, Sermadurai,Singh, Vinod K.
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- Synthesis of 2-carboxylated aza-ring derivatives through α-monohalogenation/ring-contraction of N-sulfonyl lactams
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2-Carboxylated aza-rings have been synthesized in two steps through a highly selective monohalogenation of N-sulfonylated lactams of various ring sizes (from 5- to 8-membered rings) followed by a ring contraction reaction. The selective monohalogenation of N-sulfonyl lactams has been achieved in modest to excellent yields (9 examples, 39–96%) using N-halogenosuccinimides via the in situ generation of trimethylsilyl ketene aminal derivatives. The so-obtained α-halogeno N-sulfonyl lactams were engaged in a ring opening/ring closing reaction in the presence of various alcohols or anilines under basic conditions affording 2-carboxylated aza-rings, such as azetidine, pyrrolidine or piperidine derivatives in high yields (24 examples, 61–99%).
- Sirindil, Fatih,Miaskiewicz, Solène,Kern, Nicolas,Lalaut, Arno,Felten, Anne-Sophie,Weibel, Jean-Marc,Pale, Patrick,Blanc, Aurélien
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p. 5096 - 5106
(2017/07/28)
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- Robust synthesis of N-sulfonylazetidine building blocks via ring contraction of α-bromo N-sulfonylpyrrolidinones
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A simple and robust one-pot nucleophilic addition-ring contraction of α-bromo N-sulfonylpyrrolidinones has been achieved toward α-carbonylated N-sulfonylazetidines. In the presence of potassium carbonate, various nucleophiles, such as alcohols, phenols or anilines, have been efficiently incorporated into the azetidine derivatives. Moreover, the α-bromopyrrolidinone precursors could be selectively obtained in good yields by monobromination of cheap and easily available N-sulfonyl-2-pyrrolidinone derivatives.
- Kern, Nicolas,Felten, Anne-Sophie,Weibel, Jean-Marc,Pale, Patrick,Blanc, Aurlien
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p. 6104 - 6107
(2015/01/09)
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- Preparation comprising an enzyme for asymmetrical hydrolysis of N-substituted C3-C4 cyclic imino-2-carboxylic acid ester and method of using the same
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There is disclosed an enzyme preparation comprising: (i) a styrene-divinylbenzene copolymer having fine pores with an average radius of 200 - 500?, and (ii) an enzyme capable of asymmetrically hydrolyzing N-substituted C3-C4 cyclic imino-2-carboxylic acid ester to preferentially produce an (S)-N-substituted C3-C4 cyclic imino-2-carboxylic acid, wherein said enzyme comprises an amino acid sequence as set forth in SEQ ID NO: 1 or the like.
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- TRANSFORMATION OF N-TOSYL-2-(1,3-BUTADIENYL)AZIRIDINE INTO N-TOSYL-2-ETHENYL-3-PYRROLINE.
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1,3-Butadienylaziridines or 1,3-butadienylazetidines activated by N-tosyl group smoothly rearrange to vinylpyrroline derivatives or vinylpiperidines in the presence of a catalytic amount of Pd(PPh3)4.Triphenyltin radical induced rearrangement of title compounds is also described.
- Fugami, Keigo,Miura, Katsukiyo,Morizawa, Yoshitomi,Oshima, Koichiro,Utimoto, Kiitiro,Nozaki, Hitosi
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p. 3089 - 3098
(2007/10/02)
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