Addition tosyl azide

The formation of 3-diazo-37/-indoles from the reaction of indoles with tosyl azide is catalysed by the addition of benzyltriethylammonium chloride [22]. In the absence of the catalyst, 3,3 -azoindoles are formed to the complete exclusion of the diazoindoles. 

Isodrin (56) gives with f-butyl azidoformate an isolable triazoline (addition in position QQ) which decomposes into aziridine by chromatography over neutral alumina. 55 With tosyl azide, on the other hand, only the aziridine derivative could be isolated. Both aziridines undergo a series of transformations leading to a so-called bird-cage hydrocarbon 57. ... 

On the other hand, 7-azabenzonorbornadiene bearing a tert-but-oxycarbonyl substituent in the 7-position, in spite of the bulky 7-substituent, exhibits exo selectivity in the addition of ethoxycarbonyl azide.129 Benzenesulfonyl and tosyl azides, however, give rise to a complex mixture from which no products could be characterized.129 The phenyl azide adduct has been obtained in 88% yield, but the stereochemistry is not known.1498 An orbital model for the effect of the 7-substituent, as a through-space interaction between the substituent and the syn double bond, has been suggested,150 and generalizations that may help to predict the syn-anti selectivity in these compounds have been developed.99,149,150... 

When R1 = CN, a molecule of hydrogen cyanide is lost and the 5-amino-triazole is obtained.249 Spontaneous amine elimination also occurs when R2 is hydrogen and an aliphatic secondary amino group is present,214 which is similar to what is observed in the addition of tosyl azide to /3-enamino esters233 and nitriles.402 Thermal elimination of amine proceeds more... 

Anomalous products have been observed in several cases. Azide addition to malonodinitrile yields a triazole only when the reaction is conducted in aqueous sodium hydroxide solution,425,428 and the triazoles obtained (83 and 84) are determined by the structure of the azide (Scheme 134). The product from the action of phenylcarbamyl azide is not a triazole (Scheme 134).425 Methylmalononitrile and tosyl azide lead to fragmentation products of the triazole such as imidazolone.429... 

When active methylene compounds in basic medium react with tosyl azide, triazoles are never formed (Section IV,A,4), but the unstable triazoline intermediate undergoes a diazo transfer reaction in a Dimroth-type rearrangement.447 A typical example is the addition of tosyl azide to a 1,3-diketone... 

Spontaneous isomerization of triazolines to diazo compounds can lead to addition of the latter to a second molecule of olefin, especially in the case of acrylic derivatives, resulting in a A pyrazoline, which by proto tropic rearrangement, gives the A2-compound (Scheme 149). Pyrazolines have been observed in the reactions of alkyl,67 aryl,32,282 heterocyclic,283,453 and gly-cosyl288 azides. A A pyrazoline is reported from the addition of phenyl and tosyl azides to 3,3-dimethylcyclopropene in this case the diazoimine formed by a retro-1,3-addition of the primary cyclopropanotriazoline adduct reacts with another olefin molecule.82... 

In addition to epoxides, three-membered nitrogen heterocycles, aziridines, can be obtained by means of catalytic asymmetric aziridinations (Eq. 30). To this aim, chiral ruthenium(salen) complexes 67 [56] and 68 [57] were useful (Fig. 1). The former phosphine complexes 67 gave the aziridine from two cy-cloalkenes with 19-83% ee [56]. On the other hand, terminal alkenes selectively underwent aziridination in the presence of the latter carbonyl complex 68 with 87-95% ee [57]. In these examples, N-tosyliminophenyliodinane or N-tosyl azide were used as nitrene sources. Quite recently, catalytic intramolecular ami-dation of saturated C-H bonds was achieved by the use of a ruthenium(por-phyrin) complex (Eq. 31) [58]. In the presence of the ruthenium catalyst and 2 equiv iodosobenzene diacetate, sulfamate esters 69 were converted into cyclic sulfamidates 70 in moderate-to-good yields. 

The cleavage of the triazolines formed by the addition of azides to oxo-enamines has already been mentioned in section II.B.3. This cleavage can be applied to the synthesis of diazo compounds unavailable otherwise. a-Diazobutyraldehyde (105) was obtained for the first time from a-ethyl- -dimethylaminoacraldehyde (104) and tosyl or picryl azide... 

Using diazoalkanes results in the formation of isomeric mixtures of cycloadducts.Unlike some reactants (phenyl azide, tosyl azide and diphenylnitrilimine), benzonitrile oxide, diazomethane, and A-phenylbenzylideneamine A-oxide underwent [3 4- 2] cycloaddition on mixing with lumisantonin using A -phenylbenzylideneamine A-oxide, however, gave the product cycloadduct in 8% yield.Dihydropyrazoles were obtained in some cases.Furthermore, pyrrole derivatives were obtained in low yield by intramolecular addition of an azomethine ylide to an a- and / -monocyclopropyl acrylate moiety. 

A rhodium-mediated carbene addition has been employed as the key step in a synthesis of furans. The precursors were synthesized on TentaGel-NHi resin, which was transformed into an amide (135). Subsequent formation of imides 136 with malonic ethyl ester chloride and reaction with tosyl azide gave solid-phase-bound diazo imides 137. Reaction with Rh2(OAc)4 in the presence of electron-deficient alkynes produced substituted furans 139 via the intermediate isomiinch-none 138 through a sequence of a [2-i-3]-cycloaddition to the alkyne and subsequent cycloreversion. The yields of the reaction varied in the range 50-70% (Scheme 36) [52]. 

The most widely used application of sulfonyl azides is in the azidation of enolates and other stabilized carbanions. The main challenge here is the avoidance of the diazo transfer reaction, which leads to diazo compounds and thus makes a diastereoselective animation impossible. Addition of the enolates to the sulfonyl azide proceeds rapidly at low temperatures (—78° or lower) to give the mesomeric ion 42 (Eq. 30).318 Reagents 41, the counter ion M+, the solvent, and the quenching reagent all influence the subsequent partition between azide and diazo compound. For enolates of esters (39) and N-acyloxazolidinoncs (40) the preferred reagent is trisyl azide (41a) 4-nitrobenzenesulfonyl azide (41c) promotes diazo transfer, and tosyl azide (41b) usually leads to mixtures of the two types of products. For ester enolates 39, either lithium or potassium as the... 

Diazo transfer.1 p-Toluenesulfonyl azide (which see) is commonly used for diazo-transfer reactions however, it has the disadvantage that the p-toluenesul-fonamide formed as one product is difficult to separate from the diazo compound. Hendrickson and Wolf1 found that the lithium and triethylarnine salts of p-carboxy-benzenesulfonyl azide are soluble in THF and acetonitrile, respectively, and that the triethylarnine salt of p-carboxybenzenesulfonamide is essentially insoluble in acetonitrile. In a standard procedure a solution of the carboxy azide is prepared in acetonitrile by addition of triethylarnine. The active methylene reactant is added and the carboxyamide salt separates within an hour. It is removed by filtration and the diazo product isolated by usual procedures. 2-Diazodimedone (2) was obtained by this procedure in 86% yield (the yield with tosyl azide is 42%). Several varia-... 

Cais2b found that phenyllithium can be replaced by other bases, preferably diethyl-amine or ethanolamine. A mixture of cyclopentadiene, tosyl azide, and diethylamine was allowed to stand at 0° for three days then, after addition of water, diazocyclo-pentadiene was extracted with ether (73% yield). The yield is somewhat higher when acetonitrile is used as solvent.2C... 

A number of 1-azetines have been obtained from thermolysis of cyclopropyl azides, nitriles and alkenes being side products. The cyclopropyl azides were obtained by transfer of a diazo-group from tosyl azide to cyclopropylamine anions or from carbene/carbenoid additions to vinyl azides. The azetine (1) was oxidized... 

The addition of tosyl azide to an enamine (Eq. 44) represents a potentially interesting approach. Finally, it may be possible to improve the low yield obtained in the photochemical reaction of arylnitriles with ethyl diazoacetate (Eq. 45). ... 

More recent approaches include a rhodium(II)-catalyzed intramolecular insertion reaction to form the hve-membered heterocycle. Reformatsky-imine addition of 4-bromo-4,4-difluoroacetoacetate with aldimines gave b-amino-y.y-difluoroacetoa-cetates 67 that were readily converted to the key diazo intermediates 68 through the action of tosyl azide and molecular sieve. Rhodium(II)-catalyzed intramolecular insertion followed by aromatization through loss of HF gave the functionalized pyrroles 69 (Fig. 3.29). 

Azide additions to a,P-unsatnrated systems are another method for the preparation of 1,2,3-triazoles. Cydoaddition of aryl azides to a,P-unsaturated aldehydes 88 in the presence of catalytic diethylamine and DBU afforded 1,4-disubstituted-l,2,3-triazoles 89 via an inverse electron-demand process (13CC10187). Michael addition of sodium azide with ethyhdene bisphospho-nates 90 in cydoaddition reactions via sonication afforded bisphosphono-1,2,3-triazoles 91 (13T4047).A one-pot protocol for the synthesis of 1,2,3-triazoles was prepared from unactivated alkenes with azidosulfenylation of the carbon-carbon double bond followed by the copper-catalyzed azide—alkyne cycloaddition (13JOC5031). 1,5-Disubstituted-l,2,3-triazoles 93 were synthesized from enamides 92 with tosyl azide (13AG(E)13265). Reaction of ethyl 3-(alkylamino)-4,4,4,-trifluoro-but-2-enoates 94 with mesyl azide in the presence of DBU afforded l,2,3-triazole-4-carboxylates 95 (13EJ02891). 

Finally, we examined the effect of varying the silane structure on reaction rate and selectivity. The use of tetramethyldisiloxane (TMDSO) (entry 5) showed a small but significant increase in the azide/alkane ratio (84 16 vs. 77 23 with ethanesulfonyl azide (7)). The reaction with poly(methylhydrosiloxane) (PMHS) was too slow (entry 6). However, addition of a sub-stoichiometric amount of phenylsilane was enough to give useful conversion (entry 7). Triethylsilane and triethoxysilane (entry 8 and 9) could not be used. Finally, combining tosyl azide (17) and TMDSO gave full conversion of 4-phenylbut-l-ene (3) in 3h with an improved azide/alkane ratio of 96 4 (entry 10) and 86% isolated yield. 

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