Catalysis of .alpha.-hydrogen exchange. XII. Catalysis of the dedeuteration of isobutyraldehyde-2-d by linear diamines including 1-dimethylamino-8-amino-2-octyne, a bifunctional catalyst

Abstract

The ether layer was washed consecutively with saturated NaCl solution, 2 N HC1, and saturated NaCl solution and dried over MgS04. After filtration, the solution was stripped of solvent to give 1.75 g of the ketone. Reduction of this ketone with LiAlH4, NaBH4, or LiAl(0-/-C4Hs)3H produced exclusively cis-1-OH. The ketone is very sensitive to both acid and base. This pro-cedure29 was used because contact with base is kept to a minimum. The Jones, Sarett, Oppenauer, and Moffatt procedures failed.Kinetic Runs. Buffered formolyses and acetolyses were run in solutions 0.10 M in sodium formate and sodium acetate, respectively. A 10-ml solution, 0.10 M in tosylate (cis-l-OTs), was prepared by dissolving 0.278 g (1 mmol) in 10 ml of buffered solvent already (29) D.

Bifunctional catalysis of .alpha.-hydrogen exchange of aldehydes and ketones

“…The second-order rate constants for dedeuteration of Me2CDCHO by monoprotonated diamines of the form Me2N(CH2)"NH2 (where = 2, 3, 4, and 5) are plotted as open circles in Figure 2 against the pKs of the diprotonated diamines (which measure the basicities of the monoprotonated diamines). 22,23 The catalytic activities increase monotonically with increasing basicity of the catalysts, and the basicity increases monotonically with the increasing numbers of carbon atoms between the two amino groups. (The two positive (open symbols) and acetone-d6 (solid symbols).…”

“…Bifunctional catalysis was also observed with monoprotonated Me2NCH2C=C(CH2)5NH2, where the chain between the two amino groups is long enough to permit the «-deuterium atom to be reached internally from the trans form of the intermediate iminium ion. 23 Bifunctional Catalysis of the Dedeuteration of Acetone-d6…”

Preferred Ring Sizes of Cyclic Transition States in Bifunctional Catalysis of the Dedeuteration of Isobutyraldehyde-2-d by Polyethyleniminestla$b

“…Bifunctional catalysis by l-dimethylamino-8-amino-2-octyne, which should give a transition state with a 13-membered ring, has been observed. 13 The compounds HaNfCHalmNHa, where m was 11 and 12 (corresponding to cyclic transition states with 16-and 17-membered rings), did not appear to be bifunctional catalysts,13 but this may result from the greater energy required to achieve the necessary gauche conformations in a polymethylene chain. The range 13-22 atoms obtained for the optimum cyclic transition state in the present case may depend significantly on the polyethylenimine nature of most of the ring.…”