Reductions With Nickel-Aluminum Alloy and Aqueous Alkali

Abstract

PART I. THE CARBONYL GROUPSince the report by Whitman, Wintersteiner, and Schwenk (1) on the reduction of estrone to a mixture of alpha-and beta-estradiol by a nickel-aluminum (Raney) alloy in alkaline solution there has appeared in the literature, as far as we could determine, but one instance (2) of the use of this reduction method. During the course of other investigations, we have had the opportunity to study further the reducing action of this alloy. This first paper represents the results we have obtained with compounds containing the carbonyl group.Compounds of this type usually take up hydrogen quite easily when treated with nascent hydrogen, or with hydrogen in the presence of a catalyst, to give the corresponding alcohols. Occasionally, even reduction to the hydrocarbon has been observed. A more general method of obtaining the hydrocarbon is by the Clemmensen reduction, which, however, has not always given satisfactory results (3, 4). Alternative methods for accomplishing the transformation of carbonyl compounds to the hydrocarbons are the Wolff -Kishner reduction and catalytic hydrogenation.We have found that with many carbonyl compounds our reduction method gives results comparable to those obtainable by the Clemmensen reduction. However, unlike the Clemmensen reduction, our reduction method is not specific, in that it converts carbonyl compounds to either the corresponding carbinol or the hydrocarbon, the extent of the reduction depending solely on the structure of the carbonyl compound. Carbonyl compounds of the general formula I

Expanding the Scope of Asinger Chemistry towards Enantiomerically Pure Secondary Amines and β-Aminothiols through Chemoenzymatic Derivatization of 3-Thiazolines

“…In conformity with the work reported in reference [17], thiazolidine (S)-2 (104 mg, 0.67 mmol) was dissolved in 10% aq. NaOH (50 mL), toluene (5 mL) heated at 90 • C and Ni/Al alloy (5.02 g, 50% Ni, 50% Al) were added carefully and the mixture was refluxed for 5 h. No formation of (S)-3 was observed.…”

“…Preparation according to general procedure 1 using rac-3 (crude product) yielded rac-4 (72.6 mg, 0.31 mmol, 11%) as a colorless solid. 1 [17,18], thiazolidine (S)-2 (92.6 mg, 0.58 mmol) was dissolved in H 2 O (10 mL), methanol (2% v/v) and Ni/Al alloy (1.06 g; 50 wt% Ni, 50 wt% Al) are added. The mixture was heated to 90 • C and 1% aqueous (aq.)…”

“…According to reference [17], thiazolidine (S)-2 (107 mg, 0.67 mmol) was dissolved in 10% aq. NaOH (50 mL), ethanol (5 mL) heated to 90 • C and Ni/Al alloy (5.01 g, 50% Ni, 50% Al) were added carefully and the mixture was stirred for 2 h at 90 • C. After filtration, the mixture was washed with H 2 O (40 mL) and extracted with dichloromethane (3 × 30 mL).…”

“…Therefore, we first conducted a screening of different methodologies which we considered to be suitable for the desired reductive desulfurization of this 3-thiazolidine (S)-2 using the racemic secondary amine rac-3, which was previously prepared, as a reference. The first method, which we applied in our experiments, was based on utilizing a Ni/Al-based alloy as a reducing agent following a protocol reported by Whitman et al and Tsukinoki et al (Scheme 3) [17,18]. Accordingly, a solution of (S)-2 in distilled water and methanol was treated with this Ni/Al-reducing agent, followed by adding a solution of KOH after increasing the temperature of this suspension to 90 • C. However, in these experiments, we did not observe any formation of the desired amine (S)-3.…”

Bis‐trimethylchinon‐1.4‐yl‐alkane als modellsubstanzen für polymere hydrochinon‐chinon‐redoxysysteme. VI. Synthese und untersuchung des redoxverhaltens durch potentiometrische titration und polarographie

“…Durch eine WITTIGSche Reaktion von 2.5-Dirnethoxy-trimethylbenzylphosphoniumchlorid mit 2.5-Dimethoxy-trimethylbenzaldehyd in Methanol und Lithiummethylat als Base wurde das 2.5.2'.5'-Tetramethoxy-3.4.6.3'.4'.6'-hexamethylstilben (9) hergestellt, dessen Entmethylierung und anschlieflende Oxydation das gewunschte IV ergeben sollte. Bei der Entmethylierung mit Pyridin.…”