Butyraldehyde, reduction

The preparation of the C33-C35 segment [137] began with the Horner-Emmons olefination of wo-butyraldehyde, reduction, and asymmetric epoxida-tion [39] leading to epoxy alcohol 234 (Scheme 33). Dithiane epoxide ring opening (regioselectivity 12 1), primary alcohol reduction, and secondary alcohol protection completed the synthesis of this segment ( 235). 

The most common oxidatiou states and corresponding electronic configurations of rhodium are +1 which is usually square planar although some five coordinate complexes are known, and +3 (t7 ) which is usually octahedral. Dimeric rhodium carboxylates are +2 (t/) complexes. Compounds iu oxidatiou states —1 to +6 (t5 ) exist. Significant iudustrial appHcatious iuclude rhodium-catalyzed carbouylatiou of methanol to acetic acid and acetic anhydride, and hydroformylation of propene to -butyraldehyde. Enantioselective catalytic reduction has also been demonstrated. 

Aldol reaction of campholenic aldehyde with propionic aldehyde yields the intermediate conjugated aldehyde, which can be selectively reduced to the saturated alcohol with a sandalwood odor. If the double bond in the cyclopentene ring is also reduced, the resulting product does not have a sandalwood odor (161). Reaction of campholenic aldehyde with -butyraldehyde followed by reduction of the aldehyde group gives the aHyUc alcohol known commercially by one manufacturer as Bacdanol [28219-61 -6] (82). 

Several species of bacteria under suitable conditions cause / -butyraldehyde to undergo the Canni22aro reaction (simultaneous oxidation and reduction to butyric acid and butanol, respectively) this reaction can also be cataly2ed by Raney nickel (7). The direct formation of butyl butyrate [109-21 -7] or isobutyl isobutyrate [97-85-8](Vish.ch.erik.o reaction) from the corresponding aldehyde takes place rapidly with aluminum ethylate or aluminum butyrate as catalyst (8). An essentially quantitative yield of butyl butyrate, CgH2 02, from butyraldehyde has been reported usiag a mthenium catalyst, RuH,[P(C,H,)3], (9). 

A mixture of ethyl cyanoacetate (Note 1) (56.6 g., 0.5 mole), freshly distilled butyraldehyde (43.2 g., 0.6 mole), 1 g. of palladium on carbon (Note 2), and 80 ml. of glacial acetic acid is placed in a 500-ml. bottle suitable for attachment to a low-pressure reduction apparatus. A solution of piperidine (2.0 ml., 0.02 mole) in 20 ml. of glacial acetic acid is added, and the bottle is connected to the reduction apparatus. 

Propanol with magnesium in reduction of chlorobenzene, 47, 104 Propionyl fluoride, 46, 6 n Propylamine, 46, 85 n Propylhydrazine, 46, 85 C ( Propyl) N phenylmtrone, genera tion from phenylhydroxylamme and n butyraldehyde, 46, 97 Purification of tetrahydrofuran (Warning), 46,105 4H Pyran 4-one, 2 6 dimethyl 3,5 diphenyl, 47, 54... 

An isolated enzyme is also used for the reduction in SCCO2 [20cj. H LADH was used for reduction of butyraldehyde as shovm in Figure 8.27. In this case, addition of... 

Another type of N-alkylation was achieved by the [IrCl(cod)]2-catalyzed reductive alkylation of secondary amine with aldehyde and silane (Equation 10.29) [53], For example, the treatment of dibutylamine 117 with butyraldehyde 118 and EtsSiH 119 (a 1 1 1 molar ratio amine, aldehyde and silane) or polymethyUiydrosiloxane (PMHS) in 1,4-dioxane at 75 °C under the influence of a catalytic amount of [lrCl(cod)]2, gave tributylamine 120. 

A method for the conversion of unsaturated aliphatic aldehydes to saturated aldehydes is a gentle catalytic hydrogenation. Palladium is more selective than nickel. Hydrogenation over sodium borohydride-reduced palladium in methanol at room temperature and 2 atm reduced crotonaldehyde to butyralde-hyde but did not hydrogenate butyraldehyde [57]. Nickel prepared by reduction with sodium borohydride was less selective it effected reduction of crotonaldehyde to butyraldehyde but also reduction of butyraldehyde to butyl alcohol, though at a slower rate [57]. Hydrogenation of 2,2,dimethyl-... 

Ethylhexanol is produced by aldol condensation of butyraldehyde followed by reduction. It can also be made in one step from propylene and synthesis gas converted to butanols and 2-ethylhexanol without isolating the butyraldehydes. See Chapter 10, Section 6. 

Cannizzaro reaction. Aromatic aldehydes (and other aldehydes in which a-hydrogen atoms arc absent, e.g., formaldehyde, trimcthylacetaldehyde, and a-hydroxy-tso-butyraldehyde) under the influence of strong aqueous or alcoholio alkali undergo simultaneous oxidation and reduction yielding the alcohol and corresponding acid. Thus —... 

As noted above, the butyraldehyde was reduced to the alcohol in these experiments when no carbon monoxide was added and when 1000 psi was added, but not when 300 psi was added. When no carbon monoxide was present the reduction was catalyzed by the metallic cobalt. When the 1000 psi carbon monoxide was used, it was presumed that the reaction was homogeneous, soluble dicobalt octacarbonyl or cobalt hydrocarbonyl being the catalyst. It is known, however, that at 150° a carbon monoxide pressure of at least 600 psi is needed to keep [Co(CO)4U from decomposing to cobalt metal. When only 300 psi of carbon monoxide was present, therefore, the cobalt would remain as metal and be inactive because it was poisoned by the carbon monoxide. 

The simple piperidine alkaloid coniine (for selected asymmetric syntheses of coniine see [22, 81-85]) offered a preliminary test case for hybrid radical-ionic annulation in alkaloid synthesis. From butyraldehyde hydrazone and 4-chloro-iodobutane (Scheme 4), manganese-mediated photolysis afforded the acyclic adduct in 66% yield (dr 95 5) the cyclization did not occur in situ [69, 70]. Nevertheless, Finkelstein conditions afforded the piperidine, and reductive removal of the auxiliary afforded coniine in 34% overall yield for four steps. This reaction sequence enables a direct comparison between radical- and carbanion-based syntheses using the same retrosynthetic disconnection an alternative carbanion approach required nine to ten steps [81, 85]. The potential for improved efficiency through novel radical addition strategies becomes quite evident in such comparisons where multifunctional precursors are employed. 

Butylene glycol, IV, 86, 106 from sucrose, IV, 322, 328 from wood sugars, IV, 184 Butyraldehyde, phytochemical reduction of, IV, 78... 

Similarly, (V-ethyl-l-naphthylamine was prepared in 88% yield, and (V-ethyl-, N-bu-tyl- and (V-benzyl-2-naphthylamine, and (V-ethyl- and (V-butyl-/ -toluidine were prepared in 50-64% yields.34 In the alkylation of / -toluidine and / -anisidine with butyraldehyde, N,N-dibutyl derivatives were also produced in 19 and 25% yields, respectively. The Emerson-Waters procedure was also applied to the reductive alkylation of 2-phenylpropylamines and 2-phenylisopropylamines with C1-C3 aldehydes (amine aldehyde ratio = 1 3).35 With higher aldehydes the monosubstituted products were isolated in good yields (in 48-94% yields with acetaldehyde), while with formaldehyde (V.N-dimethyl derivatives were obtained in 51-85% yields. 

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