Bicyclic Enamines. II. The Reaction of Norbornanones with Secondary Amines^1,2

Bicyclic enamines. VI. Homoallylic participation in the formation and properties of some bicyclic enamines

“…•6] heptane (5) (identified by comparison with an authentic sample5). See Table I for comparison of yields for different reaction times.…”

“…Tricyclic amine 5 (via pathway 2) was identified by comparison with an authentic sample. 5 The yield of tricyclic amine 5 increases the most markedly of the four products as the reaction time is extended as seen in Table I. Enamine 6 (probably formed via II), gas chromatography, hydrogenation to produce the identified saturated amine 9, and a low yield synthesis by the Diels-Alder reaction of 1,1-dimorpholinoethene (10)11 with cyclopentadiene followed by elimination of morpholine.…”

“…Secondary amines react with ,ß-unsaturated ketones or aldehydes in one of the following three ways: (1) nucleophilic attack of the amine on the ß carbon resulting in a ß-amino ketone or aldehyde such as structure l;4-7 (2) a combination of nucleophilic attacks of the amine on both the ß carbon and the carbonyl carbon to form a -aminoenamine such as structure 3 or an isomer thereof;8•9 (3) nucleophilic attack of the amine on the carbonyl carbon alone to form dienamine such as structure 2 or an isomer thereof10 (although many dienamines are formed via a -aminoenamine such as structure 3). The reaction of secondary amines with the bicyclo- [2.2.1 ]heptyl homoallylic ketone system by pathway types 2 and 3 has been observed when it was found that the acid-catalyzed reaction between morpholine and norbornenone (4) produced 2,5-bis(A"-morphoIino)tricyclo [2.2.1,02•6 ]heptane (5) (via pathway 2) and 2-Af-morpholinobicyclo [2.2.1 ]hepta-2,5-diene (6) (probably via pathway 3). 6 We have found that the reaction of norbornenone (4) with morpholine ivithout acid catalyst gives four products which are formed by all three pathway types.…”

Ring Opening of Donor–Acceptor Cyclopropanes with N-Nucleo­philes

“…A specific example of structural activation for electrophilic cyclopropanes was described in the works of Cook,70,71 wherein the reactions of tricyclo[2.2.1.0 2,6 ]heptan-3-one 25 with cyclic secondary amines were investigated (Scheme 11). Full conversion of 25 into amino ketones 26a-d was already detected after 2 hours, even though additional thermal and catalytic activation took place.…”

Enamines

“…The synthesis of enamines by the reaction of some ketones or aldehydes with a secondary amine can lead to saturated by-products when the enamine is heated in a nitrogen atmosphere with a catalytic amount of p-toluenesulfonic acid [48][49][50] (Eq. 10).…”