- Schmidt Reaction of ω-Azido Valeryl Chlorides Followed by Intermolecular Trapping of the Rearrangement Ions: Synthesis of Assoanine and Related Pyrrolophenanthridine Alkaloids
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The Schmidt reaction of ω-azido valeryl chlorides in the presence of an additional nucleophile was explored. The arenes, alcohols, and amines were demonstrated as the intermolecular trapping reagents for isocyanate ion and N-acyliminium ion from the Schmidt rearrangement, affording the corresponding products with moderate to excellent yields. Two 2-oxoindoles from the reaction were successfully converted into four natural alkaloids, namely, assoanine, anhydrolycorine, oxoassoanine, and anhydrolycorinone.
- DIng, Shao-Lei,Ji, Yang,Su, Yan,Li, Rui,Gu, Peiming
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p. 2012 - 2021
(2019/02/14)
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- Ligands to the (IRAP)/AT4 receptor encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr2
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Analogues of the hexapeptide angiotensin IV (Ang IV, Val1-Tyr2-Ile3-His4-Pro5-Phe6) encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr2 and a phenylacetic or benzoic acid moiety replacing His4-Pro5-Phe6 have been synthesized and evaluated in biological assays. The analogues inhibited the proteolytic activity of cystinyl aminopeptidase (CAP), frequently referred to as the insulin-regulated aminopeptidase (IRAP), and were found less efficient as inhibitors of aminopeptidase N (AP-N). The best Ang IV mimetics in the series were approximately 20 times less potent than Ang IV as IRAP inhibitors. Furthermore, it was found that the ligands at best exhibited a 140 times lower binding affinity to the membrane-bound IRAP/AT4 receptor than Ang IV. Although the best compounds still exert lower activities than Ang IV, it is notable that these compounds comprise only two amino acid residues and are considerably less peptidic in character than the majority of the Ang IV analogues previously reported as IRAP inhibitors in the literature.
- Andersson, Hanna,Demaegdt, Heidi,Vauquelin, Georges,Lindeberg, Gunnar,Karlen, Anders,Hallberg, Mathias
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p. 6924 - 6935
(2008/12/22)
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- (2-Azidomethyl)phenylacetyl as a new, reductively cleavable protecting group for hydroxyl groups in carbohydrate synthesis
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The (2-azidomethyl)phenylacetyl group (AMPA) is described as a new protecting group for carbohydrates. AMPA was introduced to carbohydrate hydroxyl groups in the presence of DCC, while its removal was conveniently achieved via Lindlar catalyst-catalyzed hydrogenation that had no influence on other protecting groups including benzyl, acyl, acetal and ketal.
- Xu, Jinghua,Guo, Zhongwu
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- Preparation of amides from acids and resin bound azides: Suppression of intramolecular lactam formation
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A new method for the formation of amides on solid phase has been developed. The procedure involves the reaction between activated acids in solution and resin bound iminophosphoranes generated from the corresponding azides and tributylphosphine. The method is particularly attractive when starting from δ azido acids since amides can form without internal cyclization to the lactam.
- Tang, Zhilian,Pelletier, Jeffrey C.
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p. 4773 - 4776
(2007/10/03)
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