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Perloline was synthesized as its chloride, 6-(3,4-dimethoxypheny1)-4-oxo-3,4-dihydrobenzo-[c][2,7]naphthyridin-6-ium chloride (lb), by utilizing the photochemical rearrangement of the N-oxide (6) of 5-(3,4-dimethoxyphenyl) benzo [c][2,7]naphthyridin-4(3 H)-one (2) to 6-(3,4-dimethoxyphenyl ) benzo [c][2,7]naphthyridine-4,5(3 H,6 H)- dione (7) ( dehydroperloline), which was then selectively reduced with sodium bis( methoxyethoxy ) aluminium hydride. The naphthyridinone (2) was prepared conveniently by reaction of 2-(3,4-dimethoxypheny1)-4-methylquinoline-3-carbonitrile (4) with dimethylformamide dimethyl acetal, and cyclization of the enamine product (5) with polyphosphoric acid.

3-(2-Aminoethyl)-7-chloro-4-methoxy-2-quinolone (7) was prepared by methylation of 7-chloro-4-hydroxy-3-(2-pnthalimidoethyl)-2-quinolone and removal of the phthaloyl group. Cyclization of the 3-(2-acetamidoethyl) derivative (9) gave, after hydrolysis, the pyrrolo[2,3-b]quinoline (12). An addition reaction with ethyl acrylate followed by reduction with aluminium hydride led to the pyrroloquinolin-1-ylpropanol (14), which was cyclized to the diazacyclopenta[jk]phenanthrene (16)via the quaternary salt (15). Hydrolysis of compound (16) gave the 6-ketone (17), whose structure was confirmed by its n.m.r. spectrum.

The librational mode of the AlH–4 ion has been observed at 286 cm–1 by the use of incoherent inelastic neutron scattering, and the predicted barrier to rotation derived. Both the frequency and the barrier are very considerably lower than in LiAlH4 and NaAlH4(at 470 and 500 cm–1 respectively) and this is discussed.

Exposure of tetrabutylammonium aluminium hydride to 60Co γ-rays at 77 K gave two species exhibiting large, nearly isotropic, hyperfine coupling to 27Al. One species, similar to that previously thought to be ·AlH–3 in irradiated lithium aluminium hydride, is now assigned to a hydroxylated impurity anion. The other, which exhibited hyperfine coupling to three equivalent protons, is clearly authentic ·AlH–3. This species was rotating in the solid matrix at 77 K, but anisotropic parameters were extracted from the spectra at 4 K. The results confirm the pyramidal character of ·AlH–3, but the estimated 3s population of 15.6% is almost equal to that for the isoelectronic radical ·SiH3(15.0%)(P. J. Krusic and J. K. Kochi, J. Am. Chem. Soc., 1969, 91, 3938; S. W. Bennett, C. Eaborn, A. Hudson, R. A. Jackson and K. D. J. Root, J. Chem. Soc. A, 1970, 348) rather than being greater, as had been previously postulated.

Investigation of NNN′N′-tetramethylmethylenediamine–aluminium hydride, (Me2N)2CH2,AlH3, by vibration spectroscopy, n.m.r., and mass spectroscopy has shown that the adduct is unstable at room temperature in both the gas and solid phases. A reaction scheme for the decomposition is presented. The pure adduct has been characterised by its i.r. spectrum and evidence is presented for the structure of the adduct and for that of NNN′N′-tetramethylpropanediamine–aluminium hydride, (Me2NCH2)2CH2,AlH3.

The compounds Me3N,AlH3, Me3N,AID3, (Me3N)2, AlH3, and (Me3N2, AID3were synthesized and their gas-phase infrared spectra recorded in the range 400 -4000 cm-1. The Raman spectrum of bistrimethylamine-alane in an excess of trimethylamine was also studied. The spectra establish that trimethylamine-alane is monomeric (C3v in which the two ligands occupy the axial positions. Previous assignments of the Al-H and Al-D stretching and deformation modes were confirmed and the Al-N stretching mode was identified for the first time. It occurs at533 cm-1 in the 1: 1 adduct and, as expected, moves to lower wavenumbers when the second ligand molecule is added, the N-Al-N stretching modes occurring at 460 and 461 cm-1 in the 2: 1 complex. Ambiguities and inconsistencies on the structure of the compounds were resolved on the basis of ready equilibration between the components and the ion and dipole-dipole under hydrogen releases H2O, CO2, and CO. For very pure graphite the point of maximum release for the three gases coincided at 550 deg C. The desorption of water under hydrogen current is accompanied by a chemisorption of hydrogen that heating under nitrogen at 900 deg C does not eliminate. The primary phenomena are described.

Four new complexes of aluminium hydride with quinuclidine (1 : 1 and 2 : 1), 1,4-dimethylpiperazine (1 : 1), and NNN′N′-tetramethyl-o-phenylenediamine (1 : 1) have been synthesised and characterised by chemical analysis, i.r. spectroscopy, and molecular weight measurements. The standard heats of formation of these and several other complexes of aluminium hydride have been derived from their heats of reaction with aqueous hydrochloric acid at 298·2 K. The following values were obtained for ΔHf°/kJ mol–1: HC[(CH2)2]3N,AlH3 109; {HC[(CH2)2]3N}2,AlH3 169; Me2N(CH2)2NMe2,AlH3 108; Me2N(CH2)3NMe2,AlH3 177; MeN[(CH2)2]2NMe,AlH3 163; o-C6H4(NMe2)2,AlH3 175. The results are discussed in terms of the structures and stabilities of the complexes.

(–)-But-3-yn-2-ol, (–)-hex-1-yn-3-ol, (–)-4-methylpent-1-yn-3-ol and (–)-oct-3-yn-2-ol have been prepared in 4—7% optical yield by reduction of the corresponding acetylenic ketones with 3-O-benzyl-1,2-O-cyclohexylidene-α-D-glucofuranose–lithium aluminium hydride complex. These alcohols have been assigned the S-configuration. The results underline the potential of the method for the preparation of asymmetric secondary carbinols.

Reduction of 9-anthryl styryl ketone and of anthracene-9,10-diyl bis(styryl ketone) by metal hydrides yields the corresponding saturated ketones, 9-anthryl phenethyl ketone and anthracene-9,10-diyl bis(phenethyl ketone), as sole products regardless of the metal hydride or the conditions used. The absence of the corresponding allylic and saturated alcohols normally associated with the reduction of αβ-unsaturated ketones by metal hydrides is attributed to the steric influence of the adjacent peri-hydrogen atoms of the anthracene ring. In the first case, steric hindrance to nucleophilic attack on the carbonyl carbon atom suppresses 1,2- in favour of 1,4-reduction and, in the second, a similar effect prevents further reduction of the enolate or enol precursors of the saturated ketones. Saturated 9-anthryl ketones may be reduced to the corresponding alcohols with lithium aluminium hydride and aluminium hydride, but not with the more selective reagents sodium borohydride and lithium tri-t-butoxyaluminium hydride.

SCHULLER and his co-workers1,2 have shown, from spectroscopic studies by the hollow-cathode technique, that hydrogen molecules forming the aluminium hydride bands come from the metal itself. I had come to a similar but more definite conclusion some time earlier, and had observed that hydrogen molecules formed a layer of aluminium hydride spaced between the well-known aluminium oxide layer at the surface and metallic aluminium underneath.

The new compounds Me3PGaH3 and Me3PGaD3 were prepared and shown by their gas-phase infrared spectra to be monomeric. The P-Ga stretching frequency was identified at 326/cm. The absence of a 2:1 adduct, (Me3P)2GaH3, was shown by tensiometric titration at -21C. Gas-phase displacement reactions indicate that trimethylamine and trimethylphosphine have similar donor strengths towards gallium hydride. The corresponding aluminium hydride adduct Me3PAlH3 could not be prepared directly, and trimethylphosphine does not displace trimethylamine from Me3NAlH3. The compound Ph3PGaH3 was prepared but readily decomposes at room temperature. The equilibrium between trimethylamine, trimethylphosphine, and their adducts with gallium hydride in benzene solution was investigated by n.m.r. spectroscopy. (Author)

The reduction of 4,6-diyn-2-en-ols with an excess of lithium aluminium hydride gives allenenes (3,5,6-trien-1-ols) as the main product and allenynes as the minor product. DL-Marasin, claimed to be the product from the reduction of non-2-en-4,6,8-triyn-1-ol, was shown to be a minor component only. Reduction with dialkoxylithium aluminium hydride gave improved yields of allenynes together with allenenes whereas the lithium aluminium hydride–butane-2,3-diol complex gave allenynes only.

Reduction of 2-ene-1,4-diones and 2-enones with di-i-butylaluminium hydride provides the corresponding unsaturated alcohols in excellent yields and this reagent appears to be superior to other metal hydrides including aluminium hydride.

The reactions of aluminium borohydride with several Lewis bases, containing donor atoms from Groups V and VI, have been studied. All the bases react initially to form 1 : 1 adducts, and those containing nitrogen or phosphorus as the donor atom then react further until 4 equivalents of ligand have been consumed; the products are then derivatives of aluminium hydride, L+A1H3 (where L = ligand) and borane, L+BH,. The infrared and the proton and llB nuclear magnetic resonance (n.m.r.) spectra of the products have been recorded, and are discussed in relation to the structure of the adducts. In addition, a comparison of the behaviour of aluminium borohydride with that of the boron hydrides is made.

The rates of reduction of a group of pp′-disubstituted benzophenones by lithium tri-t-butoxyaluminium hydride have been determined together with the relative rates of reaction with aluminium hydride. The Hammett plots obtained show that the carbonyl group acquires carbanion character in the former reaction but that there is little charge separation in the latter; this is consistent with the cyclic transition state assumed for aluminium hydride reductions. Only a small proportion of the hydrogen atoms of aluminium hydride were available for the reduction of benzophenones. Alkoxyaluminium hydrides produced as intermediates in the reduction of benzophenones, or by exchange between aluminium hydride and alkoxides, reduce aliphatic ketones preferentially.

IN a recent paper1 we have reported on some new band systems of AlH. One system was shown to belong to a 33i transition, and a full analysis of these systems has been given2. The further band system at 3600 A. has now been analysed, and is shown to belong to a 2i2 transition that accordingly must be attributed to the ionised aluminium hydride AlH+. Only the (0,0) band of these systems has been found. Perhaps this is due to the pre-dissociation which occurs in the band at k = 28 for the upper state.

SOME new band systems of aluminium hydride at 2700 A. and 4950 A. have already been reported1. Using a new construction for the aluminium electrode which permitted large energies in the arc at a high pressure of hydrogen, we have obtained the band system at 4950 A. in the first order of our 6.5 m. concave grating. The band system has been analysed and is found to belong to a 1C1 transition, where the lower term 1 is in common with the well-known band system 11. Of the three branches expected (P, Q, R) only the Q and P branch has been found, owing to the strong overlapping from the AlO bands. The following constants have been evaluated.

The formation of 2,3,6-trichloropyridine, the main product from the reduction of pentachloropyridine with lithium aluminium hydride in ether has been rationalized on the basis of addition of AIH4– across the 3- and 4-positions of the pyridine ring followed by an unusual cis-elimination. Analogous mechanistic schemes explain results obtained from reduction with lithium aluminium hydride of several substituted polychloropyridines. Pentachloropyridine has also been reduced with sodium and lithium borohydrides, diborane, and aluminium hydride.

Some reduction products (chromens, chroman-4-ols, and flavonols) obtained from isochromeno(4?,3?:2,3)chromone and its 7-methoxy derivative with lithium aluminium hydride, sodium di(2- methoxyethoxy)aluminium hydride, and catalytic hydrogenation are described. Allylic coupling is evident in isochromano(4?,3?:2,3)- chrom-3-ens, and the absence of allylic coupling in 3-alkoxyflav-3-enes is therefore attributed to the latter occurring in the conformation with the 2-aryl group axial (cf.1).

The reduction of a series of cyclic ketones with aluminium hydride has been studied under a variety of conditions. In a reappraisal of reductions using the neutral reagent further use of gas chromatography has led to more accurate product analysis than was formerly possible. Some features of reduction by borohydride and by dissolving alkali metals in alcohols are also included.

Preliminary work has been extended to some steroid ketones and has been shown to complement existing methods. The analysis of mixtures of epimeric steroid alcohols by gas chromatography is described.

Reduction of thebaine with lithium aluminium hydride–aluminium chloride mixtures gives either thebainone-A enol methyl ether or neodihydrothebaine as the major product, depending on the ratio used. A novel product, isometathebainone enol methyl ether, has been isolated from the reduction with aluminium hydride, and its structure has been confirmed by conversion into dihydrometathebainone.

Aluminium hydride, lithium tri-t-butoxy-aluminium hydride, and sodium borohydride reduce specifically the carbonyl group, the double bond, and both the carbonyl group and the double bond, respectively, of a conjugated cyclopentenone, while lithium aluminium hydride gives all three products in varying amounts depending on the reaction conditions.

Aluminium hydride, lithium tri-t-butoxy-aluminium hydride, and sodium borohydride reduce specifically the carbonyl group, the double bond, and both the carbonyl group and the double bond, respectively, of a conjugated cyclopentenone, while lithium aluminium hydride gives all three products in varying amounts depending on the reaction conditions.

6-(4-Hydroxy-3-methylbut-trans-2-enylamino)purine (zeatin), a cytokinin isolated from Zea mays, has been synthesized by a new route. β- Methylcrotononitrile was brominated with N-bromosuccinimide yielding γ- bromo-β-methylcrotononitrile, from which trans-γ-acetoxy-β- methylcrotononitrile was prepared. The alcohol derived from this acetate was converted into trans-β-methyl-γ-(tetrahydropyran-2- yloxy)crotononitrile. Reduction and acid hydrolysis gave 4-amino-2- methylbut-trans-2-en-1-ol which was made to react with 6-chloropurine to yield zeatin. ��� Several γ-alkoxy-β-methylcrotononitriles were prepared and reduced by aluminium chloride-lithium aluminium hydride to the corresponding unsaturated amines. Saturated nitrile formation also occurred in these reductions. The amines prepared were condensed with 6-chloropurine to yield a series of O-alkylzeatins. A number of other zeatin analogues were also synthesized. Two 6-methoxyalkylamino-purines were cleaved by sodium borohydride in the presence of iodine to 6-hydroxy- alkylaminopurines.