Azetidines synthesis

Azetidine synthesis Paterno-Buchi reaction Photochemical cyclizations Blanc reaction (n = )... 

Ring expansion of activated aziridines (43) with sulfur ylides also provides a synthesis of azetidines (75JOC2990, 58BSF345, 81CC417). The highly reactive sulfonium methylide (44 R = R = H) undergoes further reaction with the azetidines (46), but the reaction is satisfactory for substituted methylides. The less reactive sulfoxonium methylide (45 R = R = H)... 

Azetidine was first prepared in low yield and impure form in 1888 by treatment of 3-bromopropylamine with base (1888CB2669). Various modifications of the standard cyclization procedures have been reported (79CRV331), but by far the most efficient synthesis to date, which utilizes only readily available materials, is that outlined in Scheme 6. 

A wide variety of /3-lactams are available by these routes because of the range of substituents possible in either the ketene or its equivalent substituted acetic acid derivative. Considerable diversity in imine structure is also possible. In addition to simple Schiff bases, imino esters and thioethers, amidines, cyclic imines and conjugated imines such as cinnamy-lidineaniline have found wide application in the synthesis of functionalized /3-lactams. A-Acylhydrazones can be used, but phenylhydrazones and O-alkyloximes do not give /3-lactams. These /3-lactam forming reactions give both cis and /raMS-azetidin-2-ones some control over stereochemistry can, however, be exercised by choice of reactants and conditions. 

H-pyran synthesis from, 3, 759 bis(trimethylsiloxy) in pyrrole synthesis, 4, 333 chromene synthesis from, 3, 750 cycloaddition reactions with isocyanates, azetidin-2-ones from, 7, 261 dihydropyran synthesis from, 3, 771 fuiyl... 

Azete, trisdimethylamino-isolation, 7, 278 Azetes, 7, 237-284, 278-284 benzo fused, 7, 278 benzodiazepine fused applications, 7, 284 fused ring, 7, 341-362 structure, 7, 360 2,3-naphtho fusion, 7, 278 reactivity, 7, 279 structure, 7, 278 synthesis, 7, 282-283 Azetidine, acylring expansion, 7, 241 synthesis, 7, 246 Azetidine, 3-acyl-irradiation, 7, 239 synthesis, 7, 246 Azetidine, N-acyl-synthesis, 7, 245 Azetidine, alkyl-synthesis, 7, 246 Azetidine, 3-alkylthio-synthesis, 7, 246 Azetidine, 3-amino-synthesis, 7, 246 Azetidine, N-amino-oxidation, 7, 241 synthesis, 7, 246 Azetidine, aryl-synthesis, 7, 246... 

Azetidine, 7V-bromo-, 7, 240 Azetidine, AT-r-butyl- N NMR, 7, 11 Azetidine, AT-t-butyl-3-chloro-transannular nucleophilic attack, 7, 25 Azetidine, 3-chloro-isomerization, 7, 42 Azetidine, AT-chloro-, 7, 240 dehydrohalogenation, 7, 275 Azetidine, 7V-chloro-2-methyl-inversion, 7, 7 Azetidine, 3-halo-synthesis, 7, 246 Azetidine, AT-halo-synthesis, 7, 246 Azetidine, AT-hydroxy-synthesis, 7, 271 Azetidine, 2-imino-stability, 7, 256 Azetidine, 2-methoxy-synthesis, 7, 246 Azetidine, 2-methyl-circular dichroism, 7, 239 optical rotatory dispersion, 7, 239 Azetidine, AT-nitroso-deoxygenation, 7, 241 oxidation, 7, 240 synthesis, 7, 246 Azetidine, thioacyl-ring expansion, 7, 241 Azetidine-4-carboxylic acid, 2-oxo-oxidative decarboxylation, 7, 251 Azetidine-2-carboxylic acids absolute configuration, 7, 239 azetidin-2-ones from, 7, 263 synthesis, 7, 246... 

Azetidine-2,4-dione, l-amino-3,3-dialkyl-l-amino-anti-infiammatory activity, 7, 267 Azetidinediones synthesis, 7, 42 Azetidine-2,4-diones reactions, 7, 256 synthesis, 7, 36... 

Azetidin-2-one, l-benzyl-3,3,4-triphenyl-, 7, 249 Azetidin-2-one, l-(2-bromophenyl)-X-ray crystallography, 7, 247 Azetidin-2-one, 3-carboxy-synthesis, 7, 262 Azetidin-2-one, 3-halo-synthesis, 7, 77 ring contraction, 7, 81-82 Azetidin-2-one, 4-imino-IR spectroscopy, 7, 248 Azetidin-2-one, 1-phenyl-irradiation, 7, 255 Azetidin-2-one, 4-phenyl-reductive ring cleavage, 7, 252 Azetidin-2-one, 4-thio-IR spectroscopy, 7, 248 Azetidinones bicyclic, 7, 348-356 C NMR, 7, 348 H NMR, 7, 348 reactivity, 7, 356-358 spectroscopy, 7, 357 structure, 7, 349 synthesis, 7, 358-359 fused ring... 

A structurally unrelated agent is tazadolene (40). The synthesis of tazadolene begins with P-keto ester 37 and subsequent enamine formation with 3-amino-1-propanol followed by hydrogenolysis to give 38. This phenylhydroxymethyl compound is then dehydrated with hydrochloride acid to form olefin 39. Treatment with bromine and triphenylphosphine effects cycliza-tion to form the azetidine ring of tazadolene [10]. 

Some members of the Liliaceae accumulate free azetidine-2-carboxylic acid in a much higher concentration than that found to be lethal to mung bean seedlings, but it is not incorporated into their proteins. Fowden (43) postulated that these plants either had a proline-incorporating system which was more specific than that found in other species, or some subcellular mechanism operated to prevent the homolog from reaching the sites involved in protein synthesis. Data which supported the first suggestion were subsequently obtained (116). 

In their search for new hgands with a very high binding affinity for the nicotinic acetylchohne receptor (nAChR), potentially useful in positron emission tomography (PET) when radiolabeled with [ F], Horti et al. described the synthesis of BOC-protected 5-(azetidin-2-ylmethoxy)-2-chloro-6 -fluoro-3,3 -bipyridine via a sequential classical heating and microwave irradiation of (2-fluoro-5-pyridinyl)(trimethyl)stannane with f-butyl 2- [(6-chloro-5-... 

Interesting developments in simple azetidine chemistry continue to be reported. The apparently general acetylative dealkylation of Af-tert-butyl-3-substituted azetidines 6 (R = Bu ) in the presence of boron trifluoride provides a two-step route to azabicyclobutane 7 from 6 (R = Bu, R = Cl). An aqueous solution of 7 reacts with ethyl chloroformate to give 8. Relatively unexplored 3-azetidinones 9 (R = Ac or NO2) are available from 3-acetoxya2Ktidine 6 (R = Ac, R = OAc) which is obtained by acetylative dealkyation of 6 (R = Bu , R = OAc) <96JOC5453>. 3-Substituted azetidines can be utilized in the synthesis of polyfunctional y- and S-aminophosphonic acid derivatives <95TL9201>. 

Scheme 36 Asymmetric synthesis of 2-( l-aminoalkyl)azetidines from enantiopure 2-cyano-azetidines...

Joyeau, R. Felk, A. Guillaume, S. Vergely, I. Doucet, C. Boggetto, N. Reboud-Ravaux, M. Synthesis and inhibition of human leucocyte elastase by functionalized V-aryl azetidin-2-ones effect of different substituents on the aromatic ring. J. Pharm. Pharmacol. 1996, 48, 1218-1230. 

In the synthesis of the tetracyclic intermediates for the synthesis of isoarborinol and its CDE-antipode femenol, the stereochemistry of the Diels-Alder reaction can be varied using various Lewis-acid catalysts in aqueous media (Eq. 12.36).97 Their results show that the hydrophobic effects play an important role in enhancing reaction rates and can control product distribution. Novel 2,4-dialkyl-1-alkylideneamino-3-(methoxycarbonylmethyl)azetidines were obtained from aldazines and... 

During the stereoselective synthesis of azetidin-2-ones the reaction with 1 atm hydrogen over 10% Pd/C hydrogenated the double bond and hydrogeno-lyzed the benzyl group (Scheme 4.37).173... 

Scheme 2.92. Three-component asymmetric synthesis of 3-alkyl-4-methoxycarbonyl-azetidin-2-ones 2-386 from chiral crotonyl derivatives.

The direct, stereoselective conversion of alkynes to A-sulfonylazetidin-2-imines 16 by the initial reaction of copper(l) acetylides with sulfonyl azides, followed, in situ, by the formal [2+2] cycloaddition of a postulated A-sulfonylketenimine intermediate with a range of imines has been described <06AG(E)3157>. The synthesis of A-alkylated 2-substituted azetidin-3-ones 17 based on a tandem nucleophilic substitution followed by intramolecular Michael reaction of primary amines with alkyl 5-bromo-4-oxopent-2-enoates has been... 

P-Lactams have been used as a synthon for the preparation of a vast array of compounds. It has been reported that the reduction of 4-(haloalkyl)azetidin-2-ones with LiAlhL is a powerful method for the synthesis of stereodefined aziridines and azetidines <06OL1101>. However, reduction of 4-(haloalkyl)azetidin-2-ones with chloroalane afforded 2-(haloalkyl)azetidines, which were rearranged to 3,4-cw-disubstituted pyrrolidines and piperidines 32 <060L1105>. During these rearrangements, bicyclic azetidinium intermediates were formed which were ring opened by halides. The synthesis of a peptide-... 

Use of an interesting enamine photooxidation reaction has teen made of in the synthesis of P-lactams from 2-azetidine carboxylic esters (6.19) 625>. 

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