Bicyclization of aza-compounds by positive halide ions. II. Lactams and some related cyclizations

Abstract

. 65, 2770 (1987).Anodic oxidation of lactams in the presence of halide ions produced excellent yields of bicyclic compounds with reactants having rings in the range of eight to ten atoms (C7 to Cg). Smaller rings did not react to form bicyclic products and larger rings gave reduced yields. Attempts were made to cyclize non-cyclic amides and to bicyclize cycloheptyl and cyclooctyl acetamide with limited success. RICHARD M. ELOFSON, FAHMI F. GADALLAH et JAMES K. LAIDLER. Can. J. Chem. 65, 2770Chem. 65, (1987.Lorsqu'on soumet des lactames cycliques comportant de huit B dix atomes (C, i Cg) B une oxydation anodique en prtsence d'ions halogtnures, on obtient des composts bicycliques avec d'excellents rendements. Lorsqu'on soumet des composts cycliques plus petits i cette reaction, ils ne donnent pas de produits bicycliques alors que les composts dont le cycle est plus grand donnent de moins bons rendements. Lorsqu'on a essay6 de cycliser des amides non-cycliques ou de provoquer une bicyclisation des cycloheptyl-et cyclooctyl-acttamides, les rtsultats ont t t t mitigts.[Traduit par la revue] IntroductionWe have previously reported (1) the bicyclization of cyclic amines in moderate yields by anodic oxidation in the presence of halide ions, particularly bromide ion. Following the example of Edwards and co-workers (2-4) it was decided to attempt the bicyclization of a number of lactams by electrochemical means. Since amides are not readily attacked at anodes (5) and are much more resistant to chemical reagents, it was anticipated that more severe conditions in the form of higher anode potentials and/or higher temperatures might be required. On the other hand, since amides are resistant to direct anodic attack, any bicyclic products produced by indirect processes as described in the previous paper (1) should be safe from further degradation at the electrode. These postulates have been confirmed in the experiments described below.Because of the success with lactams it was decided to attempt to bicyclize cycloheptylacetamide and cyclooctylacetamide and to cyclize non-cyclic amides. These results, to date much less successful and preliminary in nature, are included only because no further work in this area is likely from this laboratory.

Catalyst-Controlled Diastereoselective Synthesis of Cyclic Amines via C-H Functionalization

“…It is of interest that for the transannular closure to 2n , a survey of commercial and noncommercial catalysts revealed that the homoleptic dirhodium catalyst derived from dehydroabietic acid (DBA) provided superior yields of 2n and reduced cycloheptanone formation compared to other tetracarboxylate catalysts including Rh 2 (esp) 2 . This result is especially impressive given the difficulties associated with transannular C–H aminations to form medium sized rings. , The observed reduction in α-insertion could be due to favorable interactions between the DBA ligands around the dirhodium catalyst and the substrate which increase the population of (or stabilize) the boat conformer required for productive conversion to product.…”

“…This result is especially impressive given the difficulties associated with transannular C−H aminations to form medium sized rings. 22,23 The observed reduction in αinsertion could be due to favorable interactions between the DBA ligands around the dirhodium catalyst and the substrate which increase the population of (or stabilize) the boat conformer required for productive conversion to product.…”