Cyclic Aminoacyloins and Aminoketones. IV. Dependence of Transannular Interaction Upon the Relative Location of N and C_CO¹

Synthesis of bridged azabicyclic ketones. Solvolysis of enol ether ethylene ketal N-cholramines in acidic medium

“…As shown by Leonard and co-workers (40,41) in medium ring amino ketones such as 38, the interaction of a nitrogen with a carbonyl group lowers the stretching frequency of the carbonyl (to 1681 cm-I in 38). The carbonyl frequencies observed in our molecules ranging from 1707 to 1720 cm-I (for 12, 15, 20, and 39) indicate that there is no marked interaction between the nitrogen and the carbonyl group (vc=o is about 1710 cm-I for the parent ketones).…”

A Facile Synthesis of N-Boc-azocan-5-one

“…The first was the documented precedent of the transannular interaction between the N atom and the carbonyl group of the azocanone. 10,11 The second was the search for simplicity and reproducibility of the procedure. An additional feature of our proposal is the possibility to perform further transformations on intermediate 21 (see below Scheme 3), which would expand the benefits of our protocol.…”

“…Despite its deceptively simple structure, the preparation of the unprotected form of 1 can be troublesome, as a consequence of the known transannular interaction between N and C C=O . 10,11 Scheme 1 contains the reported syntheses for 1-azocan-5-one (1). In 1955, Leonard 10 reported the preparation of N-Me-1 in 20% yield using a Dieckmann ring closure approach.…”

“…10,11 Scheme 1 contains the reported syntheses for 1-azocan-5-one (1). In 1955, Leonard 10 reported the preparation of N-Me-1 in 20% yield using a Dieckmann ring closure approach. Starting from N-benzoylated octahydro-azocine (8), Fonken 12 obtained 1 via a microbial hydroxylation, followed by Jones oxidation after a cumbersome purification procedure.…”

Molecular mechanics study of transannular amine-ketone (N?C(DOUBLE BOND)O) interaction in medium-sized heterocycles

“…11,12 As early as 1922 10 such across the ring electronic effects were first proposed to account for the observed reactivity of the alkaloid cryptopine. The 11 ᎐ 13 N ª C O interaction was found by Leonard to be more general and it was later used as an experimental basis for mapping the reaction coordinate for the nucleophilic attack of an amine on a carbonyl carbon.…”