2-Methylene aziridines

Aziridine, 2,3-diphenyl-l-(2,4,6-trinitrophenyl)-irradiation, 7, 61 Aziridine, 1,2-divinyl-rearrangement, 7, 539 Aziridine, 2,3-divinyl-rearrangement, 7, 42, 65, 539 Aziridine, N-ethyl-inversion, 7, 6 Aziridine, 2-halo-reactions, 7, 74 Aziridine, A/-halo-invertomers, 7, 6 Aziridine, 2-methyl- N NMR, 7, 11 Aziridine, methylene-ring-ring valence isomerizations, 7, 22 synthesis, 7, 92 Aziridine, iV-nitroso-reactions, 7, 74 Aziridine, iV-phosphino-inversion, 7, 7 Aziridine, 1-phthalimido-UV irradiation, 7, 62-63 Aziridine, l-(3-thienyl)-2-vinyl-rearrangement, 4, 746 Aziridine, 7V-trimethylsilyl-inversion, 7, 7 Aziridine, 1,2,3-triphenyl-irradiation, 7, 61 Aziridine, vinyl-isomerization, S, 287 Aziridinecarboxylic acid ring expansion, 7, 262 Aziridine-2,2-dicarboxylic acid, 1-methoxy-diethyl ester... 

The conformational preference of cyclohexane spiroaziridine (9) has been examined by the low temperature peak-area method, using n.m.r. spectroscopy, for which a sample of (9) 61 % enriched in at the aziridine methylene carbon was employed. 

N-(n-Butyl)>a-methylene-3-lactam (2). CO was bubbled through Pd(OAc)2 or Pd(Ph3P)4 (0.136 mmol) in CH2CI2 (4 mL) After 2 rmn PhsP (0 54 mmol) n CH2CI2 (2 mL) is added followed by aziridine 1 In CH2CI2 After 40 h, the solvent was removed in vacuum and the residue purified by prep tic (silica gel, hexane ElOAc 8 1) to yield 2 (79%)... 

With Nitrogen Nucleophiles Aziridine-2-carboxylates react with primary and secondary amines, including anilines, to give a, 3-bisamino carboxylates [71, 113]. As an example, treatment of aziridine 153 (Scheme 3.55) with diethylamine in methylene chloride afforded compound 154 in 89% yield after chromatographic separation. 

Carbanions of active methylene compounds also react with aziridine-2-car-boxylic esters to give ring-opened products [129]. The ring-opened intermediates usually cyclize spontaneously to pyrrolidones. Treatment of 190 (Scheme 3.70) with the sodium enolate of dimethyl malonate 191, for example, afforded pyrroli-done 192 in 15% isolated yield, together with 30% of the debenzoylated product 193. 

One of the key steps in the synthesis of actinomycin D (241 Scheme 3.88) and its serine analogue involved the regio- and stereoselective ring-opening of aziridine 238 with the acid 239 [138, 139]. This transformation took place in methylene... 

Of course, new variants of the (N + C=C) approach continue to be reported. Muller and coworkers, who recently reviewed the field of rhodium(II)-catalyzed aziridinations with [N-(p-nitrobenzenesulfonyl)imino]phenyliodinane <96JP0341>, have explored the application of this technology to asymmetric synthesis. Thus, treatment of c/s-p-methylstyrene (141) with PhI=NNs and Pirrung s catalyst [Rh2 (-)(R)-bnp 4] in methylene chloride medium afforded the corresponding aziridine (142) in 75% yield and 73% ee <96TET1543>. 

A novel C-3 functionalization of methylene aziridines has also been reported <06T8447>. Selective deprotonation of 98 to form 99 and the reaction 99 with an electrophile yielded 100 in good yields. In this way, a variety of alkyl groups could be selectively placed on the aziridine. These researchers also found that (S)-a-methylbenzyl substituted methylene aziridines, 101, when deprotonated and reacted with a variety of electrophiles gave 102 in moderate yields and with good diastereoselectivity. 

Ketoximes containing a-methylene group can be transformed into aziridines by the action of LAH or Grignard reagent. The reduction of dibenzyl ketoxime (1) with LAH in boiling THE led to c/i-2-phenyl-3-benzylaziridine (2) (equation 1). Similarly, 0-alkylated or acylated dibenzyl oxime derivatives were reduced . 

Two other observations are noteworthy. First, the yield of isocyanate (9) produced on photolysis of 7 in methylene chloride (an inert solvent) is 40%. Photolysis of 7 in cyclohexene leads to a 45% yield of aziridine adduct 10 and a 41% yield of isocyanate 9. Trapping the nitrene does not depress the yield of isocyanate Hence, isocyanate 9 and adduct 10 cannot be derived from the same reactive intermediate. Instead, the isocyanate must be formed from the excited state of the azide, that is, the excited azide (7 ) must partition between the formation of isocyanate and nitrene. 

A RN Imine + ketenimine Methylene aziridine+azide 79AG(E)320 75CC436... 

C=0)-halogen, 0-(C=0)-halogen, S02-halogen, N=C=0, N=C=S, N-C(=S)-N Acyclic C(=0)-S, acyclic C(=S)-0, acyclic N=C=N Anhydride, aziridine, epoxide, ortho ester, nitroso Quaternary amines, methylene, isonitrile Acetals, thioacetal, N-C-O acetals Nitro group, >1 chlorine atom... 

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