Alane enamines

Vinylamines (enamines) are reduced by alane, mono- and dichloroalane to saturated amines, and hydrogenolyzed to amines and alkenes [710]. Reduction is favored by dichloroalane while hydrogenolysis is favored by alane. Alane, chloroalane and dichloroalane gave the following results with -N-pyrrolidinylcyclohexene V-pyrrolidinylcyclohexane in 13, 15 and 22% yield, and pyrrolidine and cyclohexene in 80, 75 and 75% yields, respectively [710]. Saturated amines were also obtained by treatment of enamines with sodium borohydride [711], with sodium cyanoborohydride [103, 712] (Procedure 22, p. 210) and by heating for 1-2 hours at 50-70° with 87% or 9S% formic acid (yields 37-89%) [320]. 

Sodium bis[2-methoxyethoxy]alanate is a selective reagent for reducing the enamine double bond of linear enaminoketones, leaving the carbonyl group untouched165 (Scheme 116). 

AIBN. The C—N bond of enamines is reductively cleaved to give an alkene with alane (AlHs). ... 

Construction of the acyclic segment 395 was initiated by conversion of (-)-citronellal (392) into bromo aldehyde 393. Formation of the unsaturated aldehyde via the intermediate enamine was followed by reduction to the allylic alcohol 394. Elimination of the vinyl bromide in 394 to the acetylene was followed by the addition of trimethylaluminum to give the terminal vinyl alane. The intermediate alane was then quenched with iodine to furnish the corresponding iodo-vinyl alcohol, which was protected as the THP ether to afford 395. 

Acylated acetoacetic esters are cleaved with methanolic potassium hydroxide to give Xn-134, which car be converted to enamines XII-135 with ammonia in the presence of a small amount of ammonium nitrate. Methyl d-alanate and XH 135 in ethanol give the enamines XIl-136, which are cyclized to the 5,6-dihydro-4-pyridones using sodium methoxide in methanol. When the... 

Similarly, it has been reported that hydrocarbons can be obtained from primary amines by treatment of the amine with aqueous sodiumhydroxide andhydroxylamine-O-sulfonic acid (Scheme 10.21) and enamines, obtained from ketones and secondary amines, can be converted to alkenes by reduction with alane (AIH3) (see Coulter, J. M. Lewis, J. W. Lynch, P. P. Tetrahedron, 1968,24,4489) (Equation 10.40). 

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