Stereoselective synthesis of naturally occurring unsaturated amide alkaloids by a modified Ramberg–Bäcklund reaction

2004 ◽  
Vol 82 (5) ◽  
pp. 622-630 ◽  
Author(s):  
Yang Li ◽  
Yu Zhang ◽  
Zhi Huang ◽  
Xiaoping Cao ◽  
Kun Gao
Keyword(s):  
Potassium Hydroxide ◽  
Stereoselective Synthesis ◽  
Starting Material ◽  
Mitsunobu Reaction ◽  
Dichloromethane Solution ◽  
Naturally Occurring

A convenient and rapid approach for the synthesis of naturally occurring unsaturated amide alkaloids 1a–1n by the recently developed one-flask Ramberg–Bäcklund reaction is described. The starting material was alcohol 3, which was transformed into thiolacetate 4 using the Mitsunobu reaction. In situ cleavage of acetyl moiety of 4, followed by alkylation of the resulting thiol with appropriate chloroacetamide 5, provided the sulfide 6. Oxidation of sulfide 6 gave the corresponding sulfone 2. Treatment of the sulfone 2 with the dibromodifluoromethane in the presence of alumina-supported potassium hydroxide in dichloromethane solution afforded unsaturated amide alkaloids 1a–1n. To the best of our knowledge, the synthesis of 1e and 1i was reported for the first time.Key words: synthesis, unsaturated amide alkaloids, Ramberg–Bäcklund reaction.

scholarly journals A Short, Efficient, and Stereoselective Synthesis of Piperine and its Analogues

Synlett ◽  
2019 ◽  
Vol 30 (04) ◽  
pp. 413-416 ◽  
Author(s):  
Adriano Bauer ◽  
Jun-Hyun Nam ◽  
Nuno Maulide
Keyword(s):  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Starting Material ◽  
Nucleophilic Attack ◽  
Wide Range ◽  
Quantitative Synthesis ◽  
Pentadienoic Acid

A quantitative synthesis of piperine from commercially available starting material is presented. The synthesis relies on a stereoselective nucleophilic attack of an in situ generated cuprate onto a cyclobutene lactone. The so-formed aryl-substituted cyclobutene spontaneously undergoes a conrotatory 4π-electrocyclic ring opening to form the 4-aryl pentadienoic acid as a single diastereoisomer. The high-yielding synthesis can be easily modulated on the aryl and on the amide moiety for the synthesis of a wide range of piperine analogues.

How Artefacts Do Leadership: A Ventriloquial Analysis

2021 ◽  
pp. 089331892199807
Author(s):  
Jonathan Clifton ◽  
Fernando Fachin ◽  
François Cooren
Keyword(s):  
Organizational Communication ◽  
Recent Work ◽  
Distributed Leadership ◽  
Network Theory ◽  
Actor Network Theory ◽  
Fine Grained ◽  
Naturally Occurring ◽  
Human Actors

To date there has been little work that uses fine-grained interactional analyses of the in situ doing of leadership to make visible the role of non-human as well as human actants in this process. Using transcripts of naturally-occurring interaction as data, this study seeks to show how leadership is co-achieved by artefacts as an in-situ accomplishment. To do this we situate this study within recent work on distributed leadership and argue that it is not only distributed across human actors, but also across networks that include both human and non-human actors. Taking a discursive approach to leadership, we draw on Actor Network Theory and adopt a ventriloquial approach to sociomateriality as inspired by the Montreal School of organizational communication. Findings indicate that artefacts “do” leadership when a hybrid presence is made relevant to the interaction and when this presence provides authoritative grounds for influencing others to achieve the group’s goals.

Stereoselective Synthesis of (±)-Ireland Alcohol Using Titanium-Mediated [2,3]Wittig Rearrangement Product as a Starting Material

1992 ◽  
Vol 65 (7) ◽  
pp. 1841-1848 ◽  
Author(s):  
Satoru Ikegami ◽  
Hiroaki Okamura ◽  
Satoru Kuroda ◽  
Tsutomu Katsuki ◽  
Masaru Yamaguchi
Keyword(s):  
Stereoselective Synthesis ◽  
Starting Material ◽  
Rearrangement Product ◽  
Wittig Rearrangement

Absorption of beta-casomorphins from autoperfused lamb and piglet small intestine

1990 ◽  
Vol 259 (3) ◽  
pp. G443-G452 ◽  
Author(s):  
L. C. Read ◽  
A. P. Lord ◽  
V. Brantl ◽  
G. Koch
Keyword(s):  
Small Intestine ◽  
Intestinal Lumen ◽  
Physiological Conditions ◽  
Naturally Occurring ◽  
Gut Epithelium ◽  
Measured Absorption ◽  
Beta Casein ◽  
Kinetics Of

beta-Casomorphins (beta-CMs) derived from milk beta-casein may exert various opiate activities in milk-fed infants. To assess the physiological significance of beta-CMs as a source of circulating opioids in infants, we measured absorption rates of several beta-CMs under near-physiological conditions using in situ autoperfused lamb intestine. The naturally occurring beta-CMs, beta-CM-7 and beta-CM-4-amide, were absorbed readily into blood with no transfer into lymph. Uptake peaked within several minutes of the luminal infusion of peptide but then declined sharply and stopped within a further 10-15 min. The recovery in blood, intestinal contents, and tissue at the end of the 30-min experiment was less than 1% of the infused dose. The low recovery was due to rapid proteolysis based on in vitro studies that demonstrated half-lives of less than 5 min in lamb blood, luminal contents, and lymph. The synthetic dipeptidyl peptidase IV-resistant analogue beta-[D-Ala2]CM- 4-amide was stable during incubation in blood, lymph, or luminal contents and was absorbed into blood at rates that were maximal within several minutes and remained steady for the 30-min period. We conclude that although natural beta-CMs are transferred across the lamb small intestine, rapid degradation within the intestinal lumen, gut epithelium, and blood would prevent entry into the circulation under normal conditions. Val-beta-CM-7, a putative stable precursor, had similar stability and kinetics of absorption to beta-CM-7, results that exclude Val-beta-CM-7 as a stable precursor for delivery of beta-CMs to the circulation. Essentially identical results to those in lambs were obtained in 7-day-old piglets.

scholarly journals THE REACTION BETWEEN 2,2-DIPHENYL-1-PICRYLHYDRAZYL FREE STABLE RADICAL AND N-BROMOSUCCINIMIDE

1998 ◽  
Vol 6 (7) ◽  
pp. 101-106
Author(s):  
Petre Ionita
Keyword(s):  
Nitro Group ◽  
Stable Radical ◽  
Starting Material ◽  
Secondary Product ◽  
Ipso Substitution

The reactions of 2,2-diphenyl-1-picrylhydrazyl (DPPH) or 2,2-diphenyl-1-picrylhidrazine (DPPH-H) with N-bromosuccinimide (NBS) were studied. Two main compounds Br-DPPH and (Br)2 DPPH were obtained, by bromination of the starting material in para-phenyl position, and also a secondary product, N02 DPPH. It was shown that the reactions of NBS with DPPH include a substitution at the picryl group of PPH with liberation in situ of N02 (ipso-substitution of a nitro group with bromine) and subsequently N02 is scavenged by DPPH with the foundation of N02 DPPH.

A Metal-free and β-Stereoselective Synthesis of 2-Deoxy-C-aryl Glycosides: Synthesis of 5-aza analogues of Aquayamycin

Synlett ◽  
2021 ◽  
Author(s):  
Yuling Mei ◽  
nan jiang ◽  
Yu Yang ◽  
Wan Zhang ◽  
Saifeng Qiu ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Metal Free ◽  
Wide Range ◽  
One Step ◽  
Aryl Glycosides ◽  
Aryl Glycoside

A convenient protocol for β-stereoselective synthesis of 2-deoxy-C-aryl glycosides has been developed. This reaction takes place in one step by using I2/Et3SiH to activate glycosyl acetate to generate glycosyl iodide intermediate in situ, which was captured by naphthol followed by Fries-like O- → C-glycoside rearrangement to selectively afford β-C-aryl glycoside. The approach is applicable to a wide range of naphthol modules, and its utility was demonstrated in the synthesis of 5-aza analogues of Aquayamycin.

Supramolecular Control of Photocycloadditions in Solution: In Situ Stereoselective Synthesis and Release of Cyclobutanes

2019 ◽  
Vol 131 (12) ◽  
pp. 4026-4031 ◽  
Author(s):  
Li‐Li Ma ◽  
Yuan‐Yuan An ◽  
Li‐Ying Sun ◽  
Yao‐Yu Wang ◽  
F. Ekkehardt Hahn ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Supramolecular Control
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