Phosphoroxychlorid als Veresterungskatalysator

Abstract

127Entfernung nicht veresterter Siiuren mit 10yoiger Natriumbicarbonat-oder Natriumcarbonatlosung ausgeschuttelt, darauf mit Waaser gewaschen, SchlieBlich mit wasserfreiem Calciumchlorid getrocknet, &her verdampft und die Ester je nach ihren physikalischen Eigenschaften entweder rektifiziert oder umkristaUisiert.Bei der Veresterung der Pioolinsiiure wurde alkalisch gemacht und ausgeiithert. Der iitherische Auszug wurde erneut mit 2n-SaIzsiiure ausgezogen. Die salzaaure Losung wurde alkalisch gemacht und die Picolinsaureester ausgeiithert. Ather wurde getrocknet, verdampft und die Ester nach gewohnlichen Methoden gereinigt.Leichtfluchtige Ester, wie Essigsiiureiithylester, wurden wiihrend der Vemterung nach bekannten Arbeitsweisen ibdestilliert und die Destillate zwecks Reingewhnung der Ester entsprechend aufgearbeitet.

Synthesis of 10‐Aryl‐10H‐naphtho[1,8a,8‐fg]indazol‐7‐ones

“…The solid was collected by suction filtration and washed with water until neutral. The yield was 2.89 g (97%) brownish prisms, mp 217 °C dec (bromobenzene); ir: 3200-3340 m, 1645 m, 1570-1595 m cm -1 ; 1 H nmr: δ 1.90 (s, CH 3 ), 6.80 (dd, J = 7 + 1.5 Hz, 2 ArH), 1 ArH),7 ArH), 9.05 (s, NH), 10.00 (s, OH).…”

“…2-Acetyl-3-hydroxy-1H-phenalen-1-one (1) was obtained in a 2-step reaction from phenalene-1,3-dione by cyclocondensation with diethyl malonate, followed by a ring-opening reaction in sodium hydroxide solution and subsequent spontaneous decarboxylation upon acidification as described recently [5]. Attempts to obtain 2-acetyl-3-hydroxy-1H-phenalen-1-one (1) in a one step reaction by direct acetylation of phenalene-1,3-dione using acetic acid with acid catalysts as described in several heterocyclic systems [7] was not successful.The reaction of 2-acetyl-3-hydroxy-1H-phenalen-1-one (1) with arylhydrazines 2 was performed either in dimethylformamide without catalyst in the case of phenylhydrazine (2a) or with glacial acetic acid and sulfuric acid as catalyst in the case of 4-nitrophenylhydrazine (2b). In both cases 3-hydroxy-2-[1-(arylhydrazono)ethyl]-1H-phenalen-1-ones 3 were obtained in 48 and 97% yield, respectively.…”

Oxidative Cleavage of Pyrocatechol at the meta‐Position; A Model Reaction for Cleavage by Pyrocatechol‐2,3‐dioxygenase?

“…Y ' 3. a: R = tBu [2,3] 'ii-rs oc/ 2 was synthesized by the stepwise degradation of bis(tri-methylsily1)sulfur diimide, S(NSiMe&, in the presence of carbonyliron complexes. Compounds of the type Fe2(CO),(RNS) 3 have previously been des~ribed[~.~I; the ligand is formed by fragmentation of sulfur diimides S(NR), (R= tert-butyl[',-'I, p-t~lyl'~') or sulfinylamines RNSO (R=phenyl[21).…”

Synthesis of N1‐substituted coumarino[4,3‐c] pyrazoles

“…(7-Hydrazinocarbonylmethoxy-2-oxo-2H-chromen-4-yl)-acetic acid hydrazide 4 was obtained from (7-hydroxy -2-oxo-2H-chromen-4-yl)-acetic acid. Compounds 1a-d were synthesized from 4-hydroxy-2oxo-2H-chromen [21][22][23]. Structures of compounds 1a-d are as previously described [24][25][26][27][28].…”

“…These compounds were found to possess high antimicrobial activity against Staphyloccocus pneumoniae and were slightly less active against Bacillus subtilis, Bacillus cereus and Salmonela panama. In case of 3-alkyl-1- Starting from 4-hydroxy-2-oxo-2H-chromen using a known procedure, we have prepared 3-acyl-4-hydroxy-2-oxo-2Hchromen 1a-d [21][22][23]. We have also used known procedures for the preparation of (7-hydroxy-2-oxo-2H-chromen-4-yl)-acetic acid hydrazide 2.…”