A new pathway via intermediate 4-amino-3-fluorophenol for the synthesis of regorafenib

A practical synthetic route to regorafenib, in which the target compound was obtained via a 10-step synthesis starting from 2-picolinic acid, 4-chloro-3-(trifluoromethyl)aniline, and 3-fluorophenol, is reported. Crucial to the strategy is the preparation of 4-amino-3-fluorophenol via Fries and Beckman rearrangements using an economical and practical protocol. The main advantages of the route include inexpensive starting materials and an acceptable overall yield. A scale-up experiment was carried out to provide regorafenib with 99.96% purity in 46.5% total yield.     

A convenient synthesis of phosphoenolpyruvate via silyl-ester intermediate

Phosphoenolpyruvate was synthesized in high yield by a simple procedure starting from pyruvic acid and dimethyl trimethylsilyl phosphite through trimethylsilylation, bromination, and the Perkow reaction.     

A new synthesis of flavonoids via Heck reaction

Several naturally occurring flavonoids have been synthesised following a new proposed method based on the use of the Heck reaction. The key step involves the coupling of an aryl vinyl ketone with an aryl iodide. This procedure affords the flavonoid moiety in a single step.     

通过烯丙基碲盐合成烯丙基硫醚的新方法

本文阐述了室温下,在NaOH存在下, 烯丙基二烃基溴化亚碲经苯硫酚或硫代烷基处理, 可高产率地得到烯丙基硫醚. 这一过程提供了一个有效的合成烯丙基硫醚的新方法.     

A direct synthesis of indolocarbazoles via new dinitroterphenyl precursors

The two indolocarbazoles 2 and 4 were synthesized via the reductive ring closure of dinitrodiphenylbenzenes with triethylphosphite as reducing agent in a high boiling solvent. The electrochemical behaviour of the title systems is discussed.     

Highly enantioselective synthesis of terutroban key intermediate via asymmetric hydrogenation

A chiral (R) key intermediate of the biologically active form of terutroban has been prepared by asymmetric hydrogenation. The catalysts are based on very easily accessible ruthenium complexes modified by chiral phosphorous ligands. The use of the chiral catASium^®T ligands family allowed us to realize this transformation efficiently in terms of yield and enantioselectivity (ee up to 92%) with high substrate/catalyst ratios.     

A concise and efficient synthesis of salvinal from isoeugenol via a phenoxenium ion intermediate

In this letter, we describe how salvinal can be efficiently synthesized from isoeugenol via a phenoxenium ion intermediate by four steps in 23% over all total yield.     

A convenient synthesis of new aminomethylenedioxypyrroloindoles via an iminium salt

Cyclization of 2-(1-pyrrolyl)piperonylcarboxamide derivatives gave iminium perchlorates which afforded 9-(N-substituted-imino) and 9-(N-substituted amino)-6,7-methylenedioxypyrrolo[1,2-a]indoles.     

A new synthesis of substituted spiro butyrolactones via dyotropic rearrangement

Spiro butyrolactones bearing various α-substituents have been synthesized in three steps from acetic acid derivatives; the sequence employs a dyotropic rearrangement as its pivotal step.     

A new approach to the synthesis of 16-heteroprostanoids via isoxazole intermediates

Translated from Khimiya Geterotsiklicheskikh Soedinenii. Vol. 30. No. 3, pp. 424–425, March, 1994.     

A convenient synthesis of new aminopyrroloindoles via an imminium salt

Cyclization of pyrrolidinocarboxamide derivative of 2-(1-pyrrolyl) benzoic acid leads to an imminium salt which conduct to N-substituted 9-imino (and amino) 9H-pyrrolo[1,2-a]indoles.     

Total synthesis of pinnamine and anatoxin-a via a common intermediate. A caveat on the anatoxin-a endgame

[reaction: see text] This paper describes the total synthesis of the naturally occurring alkaloids pinnamine (1) and anatoxin-a (2) from a common enantiomerically pure intermediate (7) easily available from pyroglutamic acid. The synthesis of enantiopure pinnamine proceeded in 10 steps and 4.8% overall yield, and the route was flexible enough to allow stereocontrolled access to a non-natural congener (5-epi-pinnamine) of the natural product. Intramolecular reaction of an N-acyl iminium ion was a key step in the synthesis of both pinnamine and anatoxin-a. However, in stark contrast to literature precedent, complete racemization was observed during the reaction of the N-acyliminium ion leading to the latter alkaloid.     

A general and efficient route to enantioselective synthesis of pumiliotoxin A alkaloids via a common key intermediate

A general and efficient formal synthesis of pumiliotoxins and allopumiliotoxins has been achieved via a common key intermediate 3a. Our route featured a novel one-pot substitution-ring-opening sequence and an efficient Claisen-type condensation. This method is also applicable to quinolizidine derivative 2b.     

Design and synthesis of new cryptophanes with intermediate cavity sizes

The development of molecular imaging using hyperpolarized xenon MRI needs highly optimized biosensors. Cryptophane-111 and cryptophane-222 are promising candidates that show complementary encapsulation properties although they only differ by the length of the three alkane linkers joining two cyclotriphenolene units. Cryptophanes containing both methoxy and ethoxy linkers have never been synthesized. Here we synthesize two new cages with intermediate internal volumes, in two steps from cyclotriphenolene.     

A one-pot diastereoselective synthesis of cis-3-hexene-1,6-diols via an unusually reactive organozinc intermediate

A highly diastereoselective method for the synthesis of cis-3-hexene-1,6-diols has been developed. This new reaction proceeds with excellent control of diastereoselectivity over four stereocenters and the double bond geometry. The diols are made in a one-pot procedure involving hydroboration of a terminal alkyne and transmetalation to zinc to give a divinylzinc intermediate. This intermediate undergoes reductive elimination, forming a C=C bond. In the absence of a trapping reagent, diene is liberated (70% yield); however, in the presence of ketones or aldehydes, the proposed intermediate metallocyclopentene is trapped via a double insertion of the carbonyl substrate. Workup provides the diols in 47-86% yield.