Pyridine 1-oxide, 4-dimethylamino

Pyridine, 3-(dimethylamino)-amination, 2, 236 methylation, 2, 342 nitration, 2, 192 iV-oxide synthesis, 2, 342 Pyridine, 4-(dimethylamino)-in acylation, 2, 180 alkyl derivatives pK, 2, 171 amination, 2, 234 Arrhenius parameters, 2, 172 as base catalysts, 1, 475 hydrogen-deuterium exchange, 2, 286 ionization constants, 2, 172 methylation, 2, 342 nitration, 2, 192 iV-oxide synthesis, 2, 342... 

HOAt, 7-aza-l-hydroxybenzotriazole HATU (CAS Registry No. 148893-10-1), A-[(dimethylamino) (3//-1,2,3-triazolo(4,5- )pyridin-3-yloxy)methylene]-A-methyl-methanaminium hexafluorophosphate, previously known as G-(7-azabenzotriazol-l-yl)-l,l,3,3-tetramethyluronium hexafluorophosphate. [Note Assignment of structure to HATU as a guanidinium species rather than as a uronium species, i.e., attachment of the (Mc2NC=NMe2) unit to N3 of 7-azabenzotriazole 1-A-oxide instead of to the O, is based on X-ray analysis (ref. 33b)]. 

The compounds 93 (R = Me, Et) are extremely sensitive toward oxidation and moisture and were not isolated in a pure state. Their structures were supported by NMR spectroscopy. Treatment of 93 with pyridine also gives rise to pyridine-l-boraadamantane complex 111 and starting acetylene derivative, via 1,1-deorganoboration. Accordingly, the 1-boraadamantane-TMEDA adduct (TMEDA - bis(dimethylamino)ethane) (along with Me3SnC CSnMc() is formed when the tricyclic borane 93a (R=Me) reacts with TMEDA <2003JOM(687)108>. 

AW, Acid-washed Choi, Cholesterol DMAP, 4-(Dimethylamino)pyridine DMF, N,/V-Dimethylformamide DMTr, Di(p-niethoxyphenyl)phenyl methyl GalNAc, N-Acetylgalactosamine, 2-acetamido-2-deoxy-D-galactose HMF, 5-Hydroxymethylfur-fural, 5-(hydroxymethyl)-2-furaldehyde INOC, Intramolecular nitrile oxide-alkene cycloaddition Lea, Lewisa Lex, Lewisx MOM, Methoxymethyl MP, p-Methoxyphe-nyl MS, Molecular sieves NIS, N-Iodosuccinimide PCC, Pyridinium chlorochromate PDC, Pyridinium dichromate PMA, Phosphomolybdic acid PMB, p-Methoxybenzyl ... 

The synthesis of the furan-imidazole derivatives, shown in Scheme 2, were also described by Wang et al. [34]. Reaction of 4-(dimethylamino)benzalde-hyde (20) with trimethylsilylcyanide (TMS)-CN in the presence of Znl2 produced the TMS cyanohydrin 21. Compound 21 was treated with LDA followed by the addition of 3,4,5-trimethoxybenzaldehyde to give the benzoin intermediate 22. Oxidation with CUSO4 in aqueous pyridine, followed by reaction with 3-furaldehyde in acetic acid, produced the substituted imidazole 23. 

HATU /V-[(dimethylamino)-l//-l,2,3-triazolo[4,5-/ ]pyridin-l-ylmethylene] -A-methylmethanaminium hexafluorophosphate N-oxide (also known as <9-(7-azabenzotriazol-l-yl)-l, 1,3,3-tetramethyluronium hexafluorophosphate). 

Methacycline Methacycline, 4-dimethylamino-l,4,4a,5,5a,6,ll,12a-octahydro-3,6,10, 12,12a-pentahydroxy-6-methylen-l,ll-dioxo-2-naphthacencarboxamide (32.3.6), is synthesized from oxytetracycline (32.3.2), which is reacted with a sulfur trioxide— pyridine complex, resulting in an oxidation reaction. Simultaneous sulfonation gives a naphthacen-snlfotetrahydrofuran derivative intermediate (32.3.5), which when reacted with hydrofluoric acid forms methacycline (32.3.6) [222-225]. 

Some consideration was given to appropriate bases for this oxidation system. Pyridine and sodium bicarbonate had been shown to be useful earlier and were included. Additional bases considered were a proton sponge (1,8-Bis(dimethylamino)naphthalene) and, as stated above, pyridine N-oxide. Because of the low solubilities in CXL systems of NaHCOs and the proton-sponge, pyridine was selected for these exploratory studies. 

The number in parentheses stands for the face selectivity. Face selectivity = % ee, rms x %trans + %ecCII x %cis (reference 44). Reaction was carried out in the presence of 4-(/V,/V-dimethylamino)pyridine /V-oxide. fcThe allylic alcohol was oxidized to the corresponding aldehyde. 

An optimum yield (76%) of oxoassoanine (203), contaminated with the regioisomer (228 7%) was realised, presumably via the intermediate 229, when a mixture of 227 (1 eq.) and 4-(N,N-dimethylamino)pyridine (3 eq.) was treated with trifluoromethane sulfonic anhydride (5 eq.). Similarly the methylenedioxy analogue of 224 and 225 led to anhydrolycorinone (201) which, on oxidation, provided hippadine (202). 

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