1.2.3- Tricarbonyl compounds amines

Vinyl- and acetylenic tricarbonyl compounds are reactive dienophilic components in Diels-Alder reactions. Cycloadditions of these compounds with substituted butadienes were recently used to develop a new synthetic approach to indole derivatives [14] (Scheme 2.9) by a three-step procedure including (i) condensation with primary amines, (ii) dehydration and (iii) DDQ oxidation. 

The tricarbonyl compound 113 reacts cleanly with formaldehyde to give the lactone 115 as the first adduct 114 rapidly cyclises to the five-membered ring. The conditions are weak base and piperidine, the last of the three most popular secondary amines used in this chapter. Control is a mixture of intramolecular reaction, stable enol(ate) formation and steric hindrance.23... 

Pyridazinones were obtained from an attempted Fischer indolization of a cyclopentanone phenylhydrazone [85CI(L)697], from hydrazones of unsaturated 1,4-keto esters (87H2101) or from 3-arylhydrazones of 4-(4-methoxyphenyOglutaconic anhydride in the presence of seconday amines [83IJC(B)512]. Pyridazines 6 can be synthesized from 2-phenylhydrazones of 1,2,3-tricarbonyl compounds and phosphacumulenylides (80TL2939 85CB1709). 

Acylainino-4-acylimidazoles have been made from 3-amino-l,2,4-oxadiazoles and 1,3-dicarbonyl reagents (see Section 2.2.1 and Scheme 2.2.5). 4(5)-Acylimidazoles can be derived from 4-acylaininoisoxazoles (see Section 6.1.2 and Scheme 6.1.3). (See also the discussion in Section 2.2.1 on 4-acylimidazole synthesis.) 5-Acyl-l-arylimidazoles can be made from or-oxoketene-SJV-acetals and nitrosoaromatics (see Section 3.2 and Scheme 3.2.5), and 4-acyl-imidazoles by nitration of 1,3-dicarbonyl compounds in their enolic forms, reduction to iV-alkenylformamides and subsequent cyclization (see Section 3.2 and Scheme 3.2.4). Examples have also been isolated from reactions of 2-oximino-l,2,3-tricarbonyls and amines (see Section 4.1 and Scheme 4.1.7), from compounds such as 3-chloro-4,4-dimethoxy-2-butanone and 3,4-disubstituted 3-buten-2-ones (see Section 4.3 and Scheme 4.3.5), and by ultraviolet irradiation of 1-alkenyltetrazoles which bear an acyl group conjugated with the exocyclic double bond (see Section 6.1.2.3). 

Hanefeld and coworkers179 have recently noted that the reaction of sulfenes generated in situ from sulfonyl chlorides and tertiary amines, with vicinal tricarbonyl compounds such as indan-l,2,3-trione, alloxane, diethyl mesoxalate and 1-methyl-1,2,3,4-tetrahydroquinoline-2,3,4-trione, afford products derived mainly from ring opening of /i-sultones (equation 139). 

The synthesis of 4-pyridones proceeds (according to the retroanalysis) by cyclocondensation of 1,3,5-tricarbonyl compounds 33 or their 1,5-bisenol ethers 34 with ammonia or primary amines ... 

Yao et al. reported a chemo- and stereoselective asymmetric total synthesis of (-)-lannotinidine B 179 through two reductive amination in a domino fashion. Thus, the tricarbonyl compound 175 was treated with benzylamine in the presence of NaBH(OAc)3 to give 178 via 176 and 177 (Scheme 9.30) [90]. Similar reductive amination strategies have been apphed for several other natural products [22a]. 

A synthetic precursor, namely a tricarbonyl compound, RCH2C0(CH2)3C0 (CH2)3C0CH2R, which might be the basis for syntheses of both pumiliotoxin and histrionicotoxin class alkaloids, has been proposed (275). Initial cyclization of such a compound could lead to a cyclohexenone, followed by reductive amination and then imine formation to yield the pumiliotoxin precursor. 

A 1,2 or 1,3 unsymmetrically disubstituted arene is prochi-ral and therefore the corresponding chromium tricarbonyl compounds are chiral. (Substituted arene) complexes with amine, carboxyl, and formyl groups at the ortho position are resolved into optically active chromium complexes through corresponding diastereomeric adducts (eq 25). Biocatalysts also perform the kinetic resolution of racemic chromium complexes (eq 26). The optically active chromium complexes can be prepared by di-astereoselective ortho lithiation of the chiral benzaldehyde or acetophenone acetal complexes, and diastereoselective chromium complexation of the chiral ort/io-substituted benzaldehyde am-inals (eq 27). Catalytic asymmetric cross-coupling of meso (1,2-haloarene)chromium complex produces chiral monosubstituted complexes. The chiral (arene)chromium complexes can be used as ligands in asymmetric reactions. ... 

Tricarbonyl(naphthalene)chromium, 19 Trimethylsilyl chlorochromate, 327 Cobalt Compounds Acylcobaltate complexes, 101 [Bis(salicylidene-y-iminopropyl)methyl-amine]cobalt(II), 41 Cobalt(II) chloride, 249 Cobalt zeolites, 296 Dicarbonylcyclopentadienylcobalt, 96 Di- x-carbonylhexacarbonyldicobalt,... 

Especially characteristic were the tricarbonyl derivatives M(CO)3L3 (L = amine, NH3, etc.), but tetra- and pentacarbonyl compounds were also discovered. Recently, even dicarbonyls M(CO)2(L—L)2 and fully substituted derivatives M(L—L)3 and M(L—L—L)2 (L—L = dipyridyl, o-phenanthroline L—L—L = tripyridyl) have been synthesized from the hexacarbonyls by my former co-worker H. Behrens (5). Monosubstituted derivatives of iron pentacarbonyl Fe(CO)4L (L = NH3, amines, etc.) have been identified relatively recently (6). 

Azepine derivatives form a diene complex with (tricarbonyl)iron, leaving the third of the double bonds uncomplexed. If the 3-position is substituted, two different such complexes are possible and are in equilibrium, as seen in the 11 NMR spectrum. An ester group in the 1-position of the complex can be removed by hydrolysis to give an NH compound that, in contrast to the free 1 //-azcpinc, is stable (Scheme 82). The 1-position can then be derivatized in the manner usual for amines. The same (tricarbonyl)iron complex can, by virtue of the uncomplexed 2,3-double bond, serve as a dienophile with 1,2,4,5-tetrazines. The uncomplexed N-ethoxycarbonylazepine also adds the tetrazine, but to the 5,6-double bond. Thus, two isomeric adducts can be synthesized by using or not using the complex (Scheme 83). 

Chiral 2-substituted benzaldehyde chromium tricarbonyl complexes have been reacted with chloroacetophenone in the presence of KO-fert-Bu [544], After decomplexation, the E-epoxyketone is obtained with a high selectivity (Figure 6.88). This Darzens reaction with ClCF COO-tert-Bu is poorly stereoselective. Condensation of the same aldehydes with methyl aaylate or acrylonitrile in the presence of DABCO, followed by decomplexation, also leads highly selectively to P-hydroxyesters or -nitriles 6.105 (Y = COOMe or CN) [547] (Figure 6.88). An anti aldol product is also obtained with a high selectivity from a chromium complex and the titanium enolate of PhCF OCF COS-tert-Bu at -78°C [1281, 1282], Chiral aminals of a-ketoaldehydes react with lithium or sodium enolates of ethyl acetate. After treatment with acid, compounds 6.106 are obtained with a high enantiomeric excess (Figure 6.88). 

The use of molybdenum compounds in organic synthesis has attracted greater attention. Thus, molybdenum hexacarbonyl has been used in various reactions, such as the preparation of disulfides from sulfonyl chlorides, the alkylation of aryl derivatives, and the synthesis of 4-quinazolones from amines Oxygen has been replaced by fluorine with molybdenum hexafluoride. Molybdenum pentachloride in combination with hydroperoxides has served as oxidant Chelates of MoOg " have been investigated as catalysts for oxidations with molecular oxygen 2,2-Dichloro-7-butyrolactones have been prepared from olefins and methyl trichloracetate with cyclopentadienylmolyb-denum tricarbonyl dimer as catalyst ... 

Whereas nucleophilic addition of alkyl-lithium compounds to the optically pure arene(tricarbonyl)chromium complex (8) proceeds without asymmetric induction, the chelates (9) react to give amines (10), after hydrolysis, with optical purity of up to 94%." Replacement of the phenyl groups on the azomethine function by alkyl groups should provide an efficient route to a large number of chiral amines. 

Complexation Using Fe(CO)s and Me O. Reaction of a conjugated diene with Fe(CO)s in the presence of Trimethylamine N-Oxide resulted in the formation of tricarbonyl(l,3-diene)iron complexes. The use of amine oxides, preferably MesNO, permits fast reactions even at low temperatures. Reduction of amine oxides by Fe(CO)s has been described by Alper et al. and, in the case of trimethylamine iV-oxide, the intermediate compound trimethylaminotetracarbonyliron was isolated (eq 6). - ... 

The preparation of aminoferrocene is given in Figure 39. The compound undergoes many of the reactions typical of aromatic amines though it cannot be diazotized. Aminocyclopentadienyl manganese tricarbonyl is... 

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