Dione/diamine condensation

The first account on 1,2-dione/diamine condensation carried out mechanochemically was given by Zefirov, who investigated solid-phase synthesis of benzo[Mphenazme 3 by reaction of phenylenediamine 1 with 2,3-naphthoquinone 2 (Scheme 3.1) [1]. Synthesis was carried out in an SVM-0.4 vibrational ball mill (120mL chamber volume). Cascade reaction mechanism consists of the four reactions substitution, elimination, cyclization, and elimination. 

Further mechanochemical 1,2-dione/diamine condensation reactions were described by Kaupp and Naimi-Jamal in their subsequent article [4]. Substituted quinoxalines 9 were obtained by ball milling of equimolar amounts of o-phenylenediamines 7 and benzyls 8 (Scheme 3.3, Table 3.1). Milling beaker was heated at different temperatures through double walls with fittings for circulating... 

In a similar manner as used for 1,2-dione/diamine condensations, Kaupp carried out stoichiometric mechanochemical reactions of o-mercaptoanihne 86 with ninhydrin in the three reaction cascade (substitution, cyclization, and elimination), which gave the salt of 10a-hydroxyindeno[2,l-( ]benz[l,4]thiazin-l l(10a//)-one 89 (Schane4.23) [15], Washing of product with NaHC03 was the simple woricup in this efQcient sol-vent-free synthetic protocol. 

Benzene-1,2-diamines condense with oxalic acid or its esters to give quinoxaline-2,3-diones... 

Several dibenzo[e,g][l,4]diazocines 4 have been prepared by the condensation of biphenyl-2,2 -diamine derivatives 3 with 1,2-diones. The reaction proceeds upon simply melting the two components together, or byluxing in a high-boiling solvent. 

Benzocyclobutene-l,2-dione (11) can be condensed with benzene-1.2-diamine to provide an annulated quinoxaline (cf. Houben-Weyl, Vol. E9b/Part 2, p203), which on oxidation with hydrogen peroxide in acetic acid leads to the 1,4-diazocine derivative 12.34... 

These observations indicated that an intermolecular double condensation to give a bis N-(methylene-4-oxocoumarinyl)-l,4 aromatic diamine had occurred. Data from the elemental analysis indicated that the calculated and observed values were within the acceptable limits ( 0.4%) and in conformity with the assigned structure. In the addition of molar equivalents of 1,4-aromatic binucleophilic compounds to compound 72 we did not observe any heterocyclic compounds resulting from the further intermolecular nucleophilic attack on the single condensation product. Since the condensation of 3-(dimethylaminomethylene)-chromane-2,4-dione with aromatic binucleophilic compounds is the only route to the new coumarinic compounds, this represents a useful synthetic method. 

When cyclohexane-1,4-dione reacted with 3-aminocarbazole, the presumed initial double condensation product was dehydrogenated and 212 was actually isolated. Dichromate oxidation of this diamine gave the quinone... 

N-Substituted quinoxalines are obtained from N-substituted o-phenylenediamines. Thus methyl 2,3-dibromopropionate condenses with (V,A -bis(/7-toluenesulfonyl)-o-phenylenediamine to give l,4-bis(p-tolu-enesulfonyl)-2-methoxycarbonyl-1,2,3,4-tetrahydroquinoxaline (20).25 AVV -Disubstituted cyclohexane-1,2-diamines with suitable a/7-dihalides yield decahydroquinoxalines.26 Condensation of cyclohexane- 1,2-diones with glycine amide gives 2-oxo-5,6,7,8-tetrahydroquinoxalines.27... 

Thiochroman-3,4-diones react with various diamines to create the thiopyrano[c]pyrazine ring system, and reaction with />-anisaldehyde and NH4OAC gives a thiopyrano[c]imidazole. The base-catalyzed condensation with dibenzyl ketone yields a red [Amax = 495nm, = 8.4 X 103moldm 3cm 1] cyclopenta[c][l]-benzothiopyran-2-one 386 which gives a dibenzo[A/]thiopyran on reaction with DMAD (Scheme 101) <1994T7865>. 

No benzodiazepine has been obtained from o-phenylenediamine and 3,3-dimethylpentane-2,4-dione (38MI1 40MI1, 40MI2 63JA3354 75TL91) a monoacylated 2,3-diaminophenazine formed by self-condensation of two molecules of the diamine and subsequent reaction with the diketone has been isolated from the reaction mixture. It is possible that diazepine formation requires the presence of some enol form of a diketone. 

The synthesis of 3,4-diaminothiophene has been standardized and optimum conditions established for its condensation with a-diones to produce thieno[3,4- ]pyrazines <2002JOC9073>. Selective monocarbamoylation of 3,4-diaminothiophene has given access to several 2-alkyl-3,4-diaminothiophenes <1997T10331>. Acid-catalyzed reductive alkylation of the monocarbamate by treatment with an aldehyde and selenophenol in the presence of -toluenesulfonic acid gave the 2-alkylthiophene the carbamate could then be cleaved by means of HBr to give the diamine (Scheme 51). 

Synthesis of Enantiomerically Pure C2-symmetric Vicinal Diamines via Chirality Transfer from DPEN. Several C2-sym-metric vicinal diamines and their derivatives are prepared in optically pure form by chirality transfer from DPEN. For example, condensation of (5, 5)-DPEN with butane-2,3-dione in benzene at the reflux temperature is followed by stereoselective reduction with NaBHsCN and PPTS at -20 °C to afford the (25,35,5R,6R)-piperazine 4 and its diastereomer in a 15 1 ratio (eq 12). The crude product is purified by silica gel column chromatography. Formation of the biscarbamate followed by reductive cleavage of benzylic C-N bonds with lithium in liquid ammonia, and then removal of isobutyloxycarbonyl with HBr in acetic acid results in (/ ,/ )-2,3-diaminobutane dihydrobromide 5 in 99% ee. 

Condensation of benzene-l,2-diamine (25) with cyclohexadiene-1,2-dione (30) in a sealed tube gives in low yield initially a 5,10-dihydrophenazine which can be oxidized to the phenazine 31. Several substituted derivatives have been prepared by this method - (see also Houben-Weyl, Vol. 11/1, p 164). The most ready conversion into phenazine is by oxidative sublimation. ... 

Several Schiff-base ligands derived from the condensation of diamines and 1,3-diones were employed as tetradentate ligands for Zr. For example, the complexes ZrCl2[OCRCHC-(Me)NCH2]2 (R = CF3, Me) were derivatized and subsequently the salt... 

The condensation of pyridine-2,3-diamine with diethyl oxalate is reported to give, regardless of the amount of ester applied, a mixture of pyrido[2,3-6]pyrazine-2,3(1 f/,4//)-dione (12 25%) and ethyl /V-(3-amino-2-pyridyl)oxamate (11 75%). Sublimation of the latter compound at 3 Torr affords the cyclization product 12.14... 

Enolizable a-dioxo compounds, such as biacetyl and 1-phenylpropane-l, 2-dione, condense with iV2-phenylpyridine-2,3-diamine (20) in refluxing ethanol to give 2-methyl-3-methylene-4-phenyl-3,4-dihydropyrido[2,3-6]pyrazine (21a) and 3-methylene-2,4-diphenyl-3,4-dihydropyrido[2,3-A] pyrazine (21b), respectively, in low yield.21... 

The condensation of pyrimidine-4,5-diamine with diethyl oxalate, or its equivalent, results in pteridine-6,7-diones, and there is no opportunity for the formation of isomers. Pyrimidine-4,5-diamine and oxalic acid dihydrate react together, when heated to 160 °C under vacuum to give pteridinc-6,7(5//,8//)-dione (l).106,107... 

Quinoxaline-2,3-diones are conveniently prepared by boiling a mixture of the o-phenylenediamine with oxalic acid dihydrate in 4 M hydrochloric acid. Alternatively a mixture of the diamine is refluxed with excess diethyl oxalate under an air condenser so that the ethyl alcohol formed by intermolecular condensation is allowed to escape (Scheme 19). 6-Nitroquinoxaline-2,3-dione has been prepared by fusion of 4-nitro-o-phenylenediamine with oxalic acid at 160° in this preparation diethyl... 

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