Synthesis of heterocycles : Synthesis of 4H-1,4-benzothiazines

A new synthesis of fluorinated 4H-1,4-benzothiazines is being reported for the first time, obtained by condensing O-aminobenzenethiol with fluorinated β-diketones. An oxidative cyclisation mechanism, involving an intramolecular nucleophilic attack in an intermediate enamine system is suggested.     

Total Synthesis of Siomycin A: Completion of the Total Synthesis

The total synthesis of siomycin A ( 1 ), a representative compound of the thiostrepton family of peptide antibiotics, was achieved by incorporating the five synthetic segments A ( 2 ), B ( 3 ), C ( 4 ), D ( 5 ), and E ( 6 ). The dehydropiperidine segment A ( 2 ) was esterified with the dihydroquinoline segment C ( 4 ), and the subsequent coupling with the β‐phenylselenoalanine dipeptide segment D ( 5 ) at the segment C portion followed by lactamization between the segments A and D gave segment A‐C‐D ( 27 ). This was amidated with the pentapeptide segment B ( 3 ) at the segment A portion followed by one‐pot cyclization (between segments A and B) and elongation (with the β‐phenylselenoalanine dipeptide segment E ( 6 ) at the segment A portion), thus furnishing siomycin A ( 1 ).     

Glyphosate: Methods of Synthesis

Kinetics and Catalysis - The review describes the main chemical processes used in the preparation of glyphosate by different methods. Methods for the synthesis of glyphosate are considered, both...     

Convergent Synthesis of Naphthylisoquinoline Alkaloids: Total Synthesis of (+)-O-Methylancistrocline

A highly convergent synthesis of the methyl ether derivative 2a of the naphthylisoquinoline alkaloid ancistrocline (2) is described. The key step involves a stereoselective biaryl coupling between the chiral oxazoline 3 and the Grignard reagent 4 derived from the optically active tetrahydroisoquinoline 8. The atropisomeric mixture was then converted to the separable acetamides 11 and 12, which were obtained in a ratio of 16:84 and an overall yield of 32% for the three steps. The major atropisomer 12 was then converted into O-methylancistrocline (2a), which was identical to a semisynthetic sample derived from the related alkaloid ancistrocladinine (14).     

Synthesis of Flavans :One-Pot Synthesis of Flavans From 4-Methylcoumarins

4-Methylcoumarins (2), obtained by condensation of suitable phenols (1) with ethyl acetoacetate in the presence of sulfuric acid, lead directly to flavans (3) when refluxed with sodium hydroxide and ethanediol.     

绿色合成：一个逐步形成的学科前沿

绿色合成是有机合成化学面向新世纪的学科前沿。本文探讨绿色合成的目标及实现这一目标的一些可能途径。     

Heterocyclic Synthesis with Nitriles: Synthesis of Pyrazolopyrimidine and Pyrazolopyridine Derivatives

The reaction of N ₁-substituted-5-amino-4-cyanopyrazoles with malononitrile and diethylmalonate occurs with formation of 6-substituted pyrazolo[3,4-d]pyrimidines, and pyrazolo[3,4-b]pyridines respectively. The structures of the products and conceivable mechanisms are discussed.     

白刺新碱的化学合成、生源关系及仿生合成

白刺新碱是从中国沙漠植物白刺叶子中分离出来的生物碱.因为其特异的结构,引发了化学合成与生源关系方面的探讨.根据它与育亨宾结构的类似性,提出它可能来源于育亨宾.另一个可能则是来源于赖氨酸.以来源于赖氨酸的C(5)结构为原料的三步仿生合成取得了成功.对白刺新碱的化学合成、生源关系和仿生合成进展进行综述,以促进相关研究的进展.     

Sonochemistry: Synthesis of Bioactive Heterocycles

In recent years, green chemistry using environmentally benign reagents and conditions has become one of the most fascinating developments in the synthesis of widely used organic compounds. This review describes the theory and importance of ultrasound as an efficient tool in the synthesis of heterocyclic compounds.     

Malonic Ester Amide Synthesis: An Efficient Methodology for Synthesis of Amides

A general methodology “malonic ester amide synthesis” has been demonstrated, which uses α-substituted/unsubstituted diethyl malonates for the decarboxylative acylation of various aromatic/heteroaromatic primary/secondary amines to form one-carbon homologated amides, thus providing easy access to amides with odd/even chain lengths and an array of substituents on the alkyl/aryl part while avoiding use of acyl chlorides or peptide coupling reagents.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Flow Synthesis in Hot Water: Synthesis of the Atypical Antipsychotic Iloperidone

Inductively heated steel reactors continuously perform organic transformations in water under high temperature conditions, utilizing the unique physiochemical properties of water at subcritical conditions. We demonstrated the power of this set‐up in the continuous synthesis of the atypical antipsychotic drug iloperidone, in which we performed four out of five steps under aqueous conditions.     

Natural benzofurans: Synthesis of isopterofuran

A synthesis of the fungistatic phytoalexin, isopterofuran is described. In the key step, the benzofuran heterocycle is constructed by reaction of an o-iodophenol with a cuprous arylacetylide.     

One-Step Cyclization: Synthesis of N-Heteroalkyl-N'-tosylpiperazines

Piperazine derivatives are important intermediates in organic synthesis and useful building blocks in pharmaceutical and fine chemical industries. Currently available synthetic routes for these heterocyclic compounds have limited scope owing to the harsh reaction conditions, low yields, and multistep process. Herein, we reported a practical method for synthesis of alkyl-, alcohol-, amine-, and ester-extended tosylpiperazines under mild conditions with moderate to high yields. This protocol exhibits potential applicability in the synthesis of pharmaceuticals and natural products because of the operational simplicity and the conveniently available reactants. On the basis of the experimental and theoretical results, a plausible mechanism of aliphatic nucleophilic substitution (S(N)) in the cyclization has been postulated and evidence for the formation of a six-membered ring has also been confirmed by means of density functional theory (DFT) calculations.     

Hypervalent Iodine in Synthesis XXVI: A Convenient Synthesis of Acetylenic Tellurides

Abstract: Acetylenic tellurides have been prepared by the reaction of sodium arenetellurolates with alkynylphenyliodonium tosylates in DMF.     

Pyrazolothiazoles: Synthesis and Applications

Abstract

Methods for the preparation of various fused pyrazolothiazoles were reviewed here for the first time. The main types of fused pyrazolothiazole are pyrazolo[5,1-b]thiazoles, pyrazolo[3,4-d]thiazoles, and pyrazolo[4,3-d]thiazoles. Some research and industrial application of pyrazolothiazoles are reported.     

Nitrosoalkenes: Synthesis and Reactivity

Some α- and β-halonitrosoalkenes 1 have been synthesized and characterized. The halogen atoms of the oxime precursors 2 can be substituted by alkoxy groups. Two kinds of cycloaddition reaction of 1 have been observed: (i) reaction of the NO group with dienes gives 3, 6-dihydrooxazine derivatives 6 which isomerise to epoxyepimines 7 in most cases of β-substituted nitrosoalkenes; (ii) if 4, 5-dihydrooxazines 22 are obtained, the cycloaddition of the nitrosoalkenes as 4π-component is presumed.     

The Total Synthesis of Brevetoxin B: A Twelve-Year Odyssey in Organic Synthesis

The total synthesis of brevetoxin B has been achieved recently after a long search for a suitable pathway. This twelve-year odyssey

1 The Odyssey of Homer, translated by R. Lattimore, Harper Perenial, New York, 1975 . Homer's Odyssey, one of the western world's first two poems (the Iliad is the other), is the tale of the adventures, wanderings, and exploits of Odysseus, a Greek hero of the Trojan war, as he attempts to reach Ithaca, his home island where his wife Penelope awaits him. During his journey Odysseus has an incredible series of adventures and setbacks caused by the anger of the god Poseidon, whose son Odysseus had blinded. Finally, assisted by his patroness, the goddess Athene, Odysseus returns home to Ithaca to find and punish the suitors, evil men who tried to win his wife's hand and who squandered his wealth and corrupted his servants while he was away. Telemachus, Odysseus' son, who had his own share of adventures while growing up, facing the suitors and, looking for his father, joins him in glory and wisdom as they reestablish their throne on Ithaca. Besides Odysseus, other main characters of Odyssey are as follows: Telemachus: The son of Odysseus, who is just entering manhood, is highly conscious of his duties as a prince successor to the throne and protector of his mother as well as the need to live up to his father's reputation as a hero. His actions waver between the immature and the well-thought over as he searches for the truth about his father and desperately appeals to others for help. It is not until towards the end of the story that he exhibits great courage, skills, and confidence and one feels that he is, indeed, the son of Odysseus. Athene: She is the daughter of Zeus, goddess of wisdom, and patroness of arts and crafts. Odysseus is her favorite and protegé and she is his heroine, even though she is a goddess. She plays a leading role in all important events in the narrative, and her spirit and power always influence and assist Odysseus and Telemachus in their difficult moments. A friend and a confidant to Odysseus, she enjoys winning him over and her relationship with him, while the hero adores her and finds special comfort, companionship, and understanding in her. Poseidon: Younger brother to Zeus, god of the sea and of earthquakes, father of Polyphenus the one-eyed Cyclops whom Odysseus blinds. As a ruler of the sea and natural phenomena, Poseidon is able to place many obstacles in front of Odysseus, whom he despises. Poseidon, however, is unable to hold out against the combined pressure of the other gods, particularly Athene, of whom Odysseus is a favorite, and so eventually relents, but not before he repeatedly unleashes his anger. The Cyclops, Scylla, and The Sirens: Some of the superhuman and monstrous characters of the tale who inflicted tremendous tortures and blows at Odysseus and his men, before he finally overcame them. The Suitors: The evil noblemen of Ithaca who attempt to undermine Odysseus, win the hand of his queen, Penelope, and corrupt his palace servants. They succeed partly, wasting away a great deal of Odysseus fortune, but he eventually prevails and punishes them. Ithaca: The island kingdom of Odysseus, most likely located somewhere off the western coast of Greece and the destination of the hero in this adventure. It is interesting to compare places, events, and characters from the Odyssey to those of modern-day total synthesis, an excercise left to the imagination of the reader!

in synthetic organic chemistry was marked by several strategic and tactical routes, and resulted in numerous new synthetic methods. This article is a behind-thescenes account of the total synthesis of brevetoxin B, from its origins at the University of Pennsylvania to its completion at the University of California, San Diego, and The Scripps Research Institute, La Jolla, California.