Homolytic aziridine opening (aza variant of cyclopropylcarbinyl-homoallyl rearrangement) by addition of tributyltin radical to N-acylaziridines. Factors contributing to the regioselectivity
fell drastically with steric hindrance of the addition of Bu3Sn. to the acyl oxygen of 1. They depended to some extent on the experimental conditions for hydrogen capturing when aziridine homolysis provided a primary radical 3 or 6. The regioselectivity of (probably reversible) ring homolysis can be understood in terms of the stability of the arising radical (3, 6), of stereoelectronic control (e.g. 1i
One-Pot Synthesis of 2-Imidazolines via the Ring Expansion of Imidoyl Chlorides with Aziridines
作者:Michael R. Kuszpit、William D. Wulff、Jetze J. Tepe
DOI:10.1021/jo200101q
日期:2011.4.15
We herein report a simple and convenient one-pot synthesis of highly substituted 2-imidazolines in a regiocontrolled and stereospecific matter through the ringexpansionreaction of an imidoyl chloride with an aziridine, analogous to the Heine reaction.
The reduction of dibenzylketoxime (Ia) with LAH in boiling THF gave cis-2-phenyl-3-benzyl-aziridine (IIa) in excellent yield, together with a small amount of the expected primary amine, 2-amino-1,3-diphenylpropane (III). The LAD reduction of Ia was carried out and the position of deuterium introduced was based on the NMR data. The O-substituted derivatives of Ia, such as O-Me, O-acetyl and O-tosyl
Reaktionen mit Aziridinen, 47. Mitt. Regiospezifität und Stereoselektivität der säurekatalysierten Alkoholyse von cis-2-Benzyl-3-phenyl-1-phenylsulfonylaziridin
作者:Helmut Stamm、Dieter Speth
DOI:10.1002/ardp.19893220507
日期:——
Die Titelverbindung wird in ROH/H2SO4 ausschließlich zwischen N und C‐3 geöffnet, wobei überwiegend ein Diastereomer entsteht, so daß nur ein entsprechend kleiner Teil der Ringöffnung über ein freies Carbeniumion verlaufen kann. Die Schnelligkeit der Ringöffnung zeigt eine inverse Beziehung zur Größe von R.
Die Titelverbindung wird in ROH/H2SO4 ausschließlich zwischen N und C-3 geoffnet, wobei überwiegend ein Diastereomer entsteht, so daß nur ein entsprechend kleiner Teil der Ringöffnungfre überenium einion Die Schnelligkeit der Ringöffnung zeigt eine inverse Beziehung zur Größe von R.
Aziridines. 69. Reactions of N-Acylaziridines with Sodium Metal and Sodium Naphthalenide. Elimination of olefines
Reactions of N-acylaziridines 1a-g (N-benzoyl except 1d) with sodium or naphthalenide N-.- in THF provide a variety of products that usually arise via the aziridino ketyls 2. Homolytic ring opening of 2 generates the amidatoalkyl radicals 3. Only with a very short reaction time were small amounts of benzil or benzoylnaphthalenes obtained indicating a reversible trapping of 2 by dimerization or coupling with N-.-. Homolysis of 2 produced always the more stable 3 apart from reactions of monomethylaziridines 1c,d where the primary radical i-3c,d is kinetically favoured. The amides R(1)CONHCHR(4)CHR(2)R(3) (9: isopropylamides i-9c,d from 1c,d) were usually the main products. 9 arise from 3 either by H atom abstraction from THF (probably in sodium metal runs) or by reduction of 3 to carbanions 5 that abstract a proton from THF (N-.- runs). Addition of 5a (R(2-4) = H) to 1a gives finally the ketone 8a. Self reaction of primary radical 3a is dimerization. Self reaction of tertiary or secondary radicals is disproportionation when an allylamide arises. This isomerizes to an enamide unless it is conjugated.R(2)R(3)C=CHR(4) and R(1)CONH(2) arise (probably) always. The mechanism, possibly a cyclic process of anion 6, is not clear.