Aziridine, Acyl

We may thus remark that the conformational results for aziridine acyl derivatives retain the undoubtedly positive aspect of evidencing the ensemble of effects causing the internal mobility of these molecules nevertheless more efforts seem necessary to achieve more precise definition of the conformer... 

N-Inversion in azetidine and azetidin-2-one is rapid, even at —77 and -40 °C, respectively (B-73NMR144). Again, halo substituents on nitrogen drastically slow the inversion rate, so that Af-chloro-2-methylazetidine can be separated into two diastereomers (b-77SH(1)54). Substituent effects on N-inversion are much the same as in the aziridines Af-aryl and N- acyl... 

Oxaziridines unsubstituted at nitrogen as well as some iV-acylated oxaziridines offer synthetic potentialities due to their ability to transfer their nitrogen function to nucleophiles (Section 5.08.3.1.4). The simplicity of preparation of some aziridines from alkenes and the Spiro oxaziridine (S2) equals the simplicity of epoxidation. Aziridine (299), for example, is obtained by simple heating of indene with (52) in toluene (74KGS1629). 

The addition of diazo compounds generally leads to three membered tings, although in special cases, linear adducts with an intact diazo group [110] or l,3,4-oxadiazol-3-ines [111] can be isolated Most diazo compounds are unstable and yield oxirans and aziridines [112,113,114] Aziridines are obtained exclusively on reaction of certain polyfluorinated acyl imines with diazomethane [115]... 

In contrast to the reaction of the betaine 58 in wet diethylether, wet THF, in which the betaine is better soluble, gives the methyl isoanhydroberberilate 64 in 71% yield. The mechanism seemingly involves an unusual carbon to nitrogen acyl migration as shown in Scheme 23. Hydration and air oxidation of the betaine to the peroxide leads to the formation of an aziridine intermediate and loss of a hydroxide anion (77TL3787). 

Yet another nontricyclic antidepressant consists of a relatively simple morpholine derivative. Acylation of aziridine with p-chlorobenzoyl chloride gives the amide 130. This intermediate is. sufficiently reactive to undergo ring opening on treatment with morpholine. The product is the antidepressant agent moclobemide (131) 33J. 

Thermolysis of acyl azides and subsequent cyclization to give aziridines has been reported by Egli and Dreiding [39]. Heating of acylazide 34 (Scheme 3.11) in an autoclave afforded aziridine 35 in 74% yield [39]. 

Kinetic resolution of the racemic aziridine-2-carboxylate 82 (Scheme 3.26) was reported by Iqbal and co-workers [74], When 82 was allowed to react with N-cinna-moyl-L-proline (81) under mixed anhydride coupling conditions, the N-acyl azir-idine 83 was obtained in optically pure form along with aziridine 84. 

Scheme 12.20 Influence of the nitrogen substituent (sulfonyl, acyl) on the regioselectivity of aziridine opening.

Bei der Reduktion konnen sich neben den sek. Aminen auch Aziridine Widen13. O-Alkyl-14 und O-Acyl-oxime15 mit analoger Struktur werden durch Lithiumalanat ahnlich umgelagert. Durch Zugabe von Tit-an(lV)- Oder Eisen(III)-chlorid kann die Umlagerung zum sek. Amin unterdriickt werden16. 

Acyl chlorides react with epoxides in the presence of a Eu(dpm)3 catalyst or a YCp2Cl catalyst (where Cp is cyclopentadienyl) to give chloro esters. A related reaction with epi-sulfides leads to 2-chlorothio-esters. Aziridines have been opened with MgBr2 to give 2-haloamides in a related reaction. 

Reactive structures that interfere with the biochemical assay (aldehydes, acyl-halides, sulfonyl-halides, Michael acceptors, epoxides, aziridines, oximes, N-oxides). 

Thioacetals eliminate to vinylsulfides in the presence of CuOTf (Scheme 46).192 Cu1 and Cu11 triflates are mild Lewis acids for Friedel-Crafts acylation and alkylation reactions. CuOTf effectively catalyzes the reaction of anisole with selenoesters.193,194 Copper(II) sulfate promotes epoxide ring opening reactions in the presence of pyridine,195 with retention of configuration being observed. Cu(OTf)2 is a catalyst for the ring opening of aziridine by aniline.196... 

Acyl azides 268, derived from furan, thiophene and selenophene, add slowly at room temperature to the strained double bond of 5-methylenebicyclo[2.2.1]hept-2-ene. Two regioisomeric triazolines, 269 and 270, which form in the first step, are unstable and decompose with elimination of nitrogen to provide aziridine derivatives 271. Products 271 are isolated in good yield (73-85%). It is worthy to note that not only the terminal, unstrained double bond in the starting material, 5-methylenebicyclo[2.2.1]hept-2-ene, is unaffected, but also the typical dipolarophiles like esters of crotonic, propiolic and byt-2-ynoic acids do not react with azides 268 under these conditions (Scheme 39) <2002J(P1)1420>. 

Several new syntheses of the oxazolidinone ring have been published. Treatment of spoxyurethane 184 with a strong base induced the cyclisation to oxazolidinone 185 which, trough an olefine methathesis afforded 186 . Treatment with iron salt of acyl azide 187 afforded an aziridine, which, upon nucleophilic attack of a chloride ion, was transformed in the final oxazolidinone 188 <00CC287>. 

Stamm, H. and Gerster, G., Reactions with aziridines. XXI. The (Michaelis-) Arbuzov reaction with N-acyl aziridines and other amidoethylations at phosphorus, Tetrahedron Lett., 1623, 1980. 

The reactions of alkyl nitronates (164) or (165) derived from a-functionalized primary AN with monosubstituted acetylenes produce mixtures of diastereomeric aziridines (166) in moderate to high yields. Most probably, the first step of this process involves normal concerted cycloaddition to give the corresponding intermediates A, which were not detected due to their fast rearrangement to give acyl-substituted aziridines (166). The reaction is regioselective and stereospecific. The latter fact was demonstrated by French researchers (95). 

In this reaction, isoxazole (173) rather than the corresponding aziridine was isolated in good yield. It was stated (223) that acyl nitronate (172) rather than the corresponding nitrile oxide is a precursor of isoxazole (173). This interpretation is supported by the fact that the corresponding nitrile oxide dimer (furoxan (174))... 

The (aziridin-l-ylimino)phosphoranes (57) react with ketens to give nitrile derivatives, presumably from an intermediate ketenimine by breaking the N—N bond and migration of the aziridinyl group.60 They also react with acyl halides and... 

The alkene (5 mmol) in PhMe (8 ml) is stirred with the W-acyl arylhydroxylamine (0.52 mmol) and the chiral catalyst (0.05 mmol) in aqueous NaOH (33%, l ml) at room temperature for 2.5 h. A further amount (0.05 mmol) of catalyst is added and the mixture stirred for an additional 2 h. The solvent and excess alkene are removed under vacuum and the residue is taken up in Et20 (15 ml). The extract is washed with H20 (3 x 20 ml), dried (Na2S04), and evaporated to yield the aziridine. ( Higher ee is achieved using 9% aqueous NaOH.)... 

The aza-Payne rearrangement and its use as a synthetically valuable equilibration process has been reviewed. Unusual diazadioxabicyclo[2.2.2]octanes (352) have been obtained by the acid-catalysed rearrangement of A -quinazolinonyl- and A -phthalimido-aziridines derived from 3-phenylcyclohex-2-enol. ° A probable mechanism is outlined in Scheme 108. A-Acyl-2,2-dimethylaziridines have been isomerized by sodium iodide into three isomers whose yields appear to depend... 

C, and then three molecular equivalents of acetyl chloride and triethy-lamine were added. Three types of acetylated materials, 11, 12, and 13, were isolated accompanied by a small amount of thioketone 7 and thioamide 9 (Scheme 8 and Table 6). All of the acetylated materials showed optical activity. For the reaction of 6a, 84% ee of 2-(acetylthio)aziridine 11a, 50% ee of 4-(acetyl-thio)oxazoline 12a, and 20% ee of 4-(acetylthio)oxazolidin-2-one 13a were obtained in 39,10, and 16% yields, respectively. In the reaction of 6b,c, the corresponding optically active materials 11-13 were obtained as shown in Table 9. The formation of oxazoline 12 involves the rearrangement ofAT-acyl aziridines, which occurs by intramolecular attack of the carbonyl oxygen at the ring carbon to cause rupture of the system. 

---