Lewis acid-promoted 3-aza-Cope rearrangement of N-alkyl-N-allyl enamines
摘要:
The 3-aza-Cope rearrangement of the N-alkyl-N-allylenamines derived from isobutyraldehyde, which proceeds thermally at 250-degrees-C, has been accelerated by a variety of electrophilic reagents to give gamma,delta-unsaturated imines. Protic acids, such as HCl (0.5 equiv), and the Lewis acidic reagents TiCl4 (0.1-0.2 equiv), Et2O.BF3 (0.5 equiv), and AlMe3 (1.0 equiv) produced complete [3,3] rearrangement of substrates at 111-degrees-C. By increasing the Lewis acidity of the aluminum reagents, this transformation was achieved at 50-degrees-C with ClAlMe2, Cl2AlMe, and methylaluminum bis(2,6-diphenylphenoxide). Reaction conditions were studied initially by GLC analysis of the N-isobutyl derivative. These optimum conditions were then used to obtain isolated yields of 59-99% for rearrangement and in situ LiAlH4 reduction of the analogous N-methylcyclohexyl substrate to the corresponding delta,epsilon-unsaturated amine. Substrates derived from 2-phenylpropanal, n-butanal, cyclohexanone, and cyclopentanone were used to examine the general effectiveness of HCl, TiCl4, and AlMe3 as reagents for acceleration of the [3,3] rearrangement. The most versatile and efficient reagent for promoting this reaction, AlMe3, produced overall yields of 83-96% for the two-step rearrangement and reduction of these substrates.
Lewis acid-promoted 3-aza-Cope rearrangement of N-alkyl-N-allyl enamines
摘要:
The 3-aza-Cope rearrangement of the N-alkyl-N-allylenamines derived from isobutyraldehyde, which proceeds thermally at 250-degrees-C, has been accelerated by a variety of electrophilic reagents to give gamma,delta-unsaturated imines. Protic acids, such as HCl (0.5 equiv), and the Lewis acidic reagents TiCl4 (0.1-0.2 equiv), Et2O.BF3 (0.5 equiv), and AlMe3 (1.0 equiv) produced complete [3,3] rearrangement of substrates at 111-degrees-C. By increasing the Lewis acidity of the aluminum reagents, this transformation was achieved at 50-degrees-C with ClAlMe2, Cl2AlMe, and methylaluminum bis(2,6-diphenylphenoxide). Reaction conditions were studied initially by GLC analysis of the N-isobutyl derivative. These optimum conditions were then used to obtain isolated yields of 59-99% for rearrangement and in situ LiAlH4 reduction of the analogous N-methylcyclohexyl substrate to the corresponding delta,epsilon-unsaturated amine. Substrates derived from 2-phenylpropanal, n-butanal, cyclohexanone, and cyclopentanone were used to examine the general effectiveness of HCl, TiCl4, and AlMe3 as reagents for acceleration of the [3,3] rearrangement. The most versatile and efficient reagent for promoting this reaction, AlMe3, produced overall yields of 83-96% for the two-step rearrangement and reduction of these substrates.
Novel substituted 11-aminoundecanols of the formula ##STR1## and a process for their preparation are described; in the formula, R.sub.1 and R.sub.3 independently of one another are hydrogen or alkyl having 1-8 C atoms and R.sub.2 and R.sub.4 independently of one another are alkyl having 1-8 C atoms, or R.sub.1 and R.sub.2 and/or R.sub.3 and R.sub.4 together with the bonding C atom form a cycloaliphatic ring having 4-8 C atoms, and R.sub.5 and R.sub.6 independently of one another are hydrogen or alkyl having 1-4 C atoms. The compounds of the formula I are valuable active compounds for combating plant pests.
Compounds of the formula ##STR1## and a process for their preparation by reacting azabutadienes with dienes, especially 1,3-butadiene, in the presence of catalysts are described. In the formula I, R.sub.1 and R.sub.3 independently of one another are hydrogen or alkyl having 1-8 C atoms and R.sub.2 and R.sub.4 independently of one another are alkyl having 1-8 C atoms, or R.sub.1 and R.sub.2 and/or R.sub.3 and R.sub.4 together with the bonding C atom form a cycloaliphatic ring having 4-8 C atoms, and R.sub.5 and R.sub.6 independently of one another are hydrogen or alkyl having 1-4 C atoms. The compounds of the formula I are valuable intermediates for the preparation of active compounds for combating plant pests.
Substituted 11-amino-undeca-4,8-dienal and 11-amino-undecanal
申请人:Ciba-Geigy Corporation
公开号:US04277621A1
公开(公告)日:1981-07-07
Novel substituted 11-amino-undeca-4,8-dienal and 11-amino-undecanal aldehyde-derivatives of the formulae Ia ##STR1## in which R.sub.1 to R.sub.6, Y and m are as defined in patent claim 1, and processes for their preparation are described. The compounds of the formulae Ia and Ib can be catalytically hydrogenated to novel 1,11-diaminoundecanes, which, in turn, can be used, for example, for the preparation of polycondensation products, in particular transparent polyamides, or as curing agents for epoxide resins.
A high-yield synthesis of 3,3-difluoroazetidines was developed by a monochlorohydroalane reduction of 3,3-difluoroazetidin-2-ones. The latter compounds were conveniently synthesized by a Reformatsky-type reaction of aldimines with ethyl bromodifluoroacetate.
There are described compounds of the formula ##STR1## wherein R.sub.1 and R.sub.2 independently of one another represent alkyl having 1-8 C atoms, or together with the bond C atom they represent a cycloaliphatic ring having 4-8 C atoms, and R.sub.3 represents ethyl; or wherein R.sub.1 represents alkyl having 1-8 C atoms, R.sub.2 represents hydrogen, or alkyl having 1-8 C atoms, and R.sub.3 represents tertiary alkyl having 4-8 C atoms. The compounds of the formula I can be produced in a simple manner, in good to very good yields, by isomerisation of suitably substituted allylamines in an inert organic solvent and in the presence of a catalyst. The compounds of the formula I constitute valuable intermediates for producing active substances for combating plant pests.