Mesyl azide

Acetoacetyl-3,4-dihydro-2(lF/)-qumoxahnone (211) with mesyl azide gave 4-(2-diasoacetoacetyl)-3,4-dihydro-2(lF/)-quinoxahnone (212) (Et3N, MeCN, 20°C, 8 h 91% of crude), which underwent deacetylation to afford 4-diazoacetyl-3,4-dihydro-2(lF/)-qumoxalmone (213) (NaOH, THF, H2O, 20°C, 1 h 69%) ... 

Alternatively, the triazole intermediate may be assembled via a 1,3-dipolar cycloaddition of the enol and mesyl azide ... 

The 2,2 -bisindole (1384), required for the synthesis of staurosporinone (293) and the protected aglycon 1381, was prepared by a double Madelung cyclization as reported by Bergman. For the synthesis of the diazolactams 1382 and 1383, the glycine esters 1385 and 1386 were transformed to the lactams 1389 and 1390 by DCC/DMAP-promoted coupling with monoethyl malonate, followed by Dieckmann cyclization. The lactams 1389 and 1390 were heated in wet acetonitrile, and then treated with mesyl azide (MsNs) and triethylamine, to afford the diazolactams 1382 and 1383. This one-pot process involves decarboethoxylation and a diazo transfer reaction (Scheme 5.234). 

When 4-dodecylbenzenesulfonyl azide is used for the diazo transfer reaction, the crude reaction product is contaminated with by-products that cannot be separated during basic workup, and consequently column chromatography is required lor the purification of the diazo ketone. Use of mesyl azide for the diazo transfer reaction allows purification of the crude reaction product by recrystallization from diethyl ether-pentane to obtain 10.11 g (86%) of the desired diazo ketone. 

Applying Danheiser s method (96JOC134), phenyldiazenyl ketone 67 reacts with lithium bis(trimethylsilyl)amide in absolute tetrahydrofuran followed by 2,2,2-trifluoroethyl triflate forming a mixture of C- and O-triflate intermediates 68 and 69, respectively. Upon treatment with mesyl azide, the mixture of 68 and 69 provides the desired l-diazo-4-methyl-4-[(E)-phenyldiazenyl]pentan-2-one (58) as yellow crystals in very good yield (87%) (Scheme 16). 

The Regitz reaction involves the transfer of a diazo group from the tosyl azide or mesyl azide to active methylene compounds such as 1,3-diketones and their derivatives (1) in the presence of a base leading to 2-diazo-l,3-diketones (2). 

Regitz diazo transfer reactions have been reviewed previously.1-3 The following two main routes have been known for the synthesis of diazo compounds (1) diazotization of amines, oximes, nitrosoamines, and hydrazones (2) transfer of the diazo function from tosyl or mesyl azides to active methylene compounds. 

Mesyl azide is reported to be superior to the commonly used tosyl... 

This carbene insertion reaction has been used in a variety of syntheses, and is especially attractive when coupled with other synthetic techniques. Taber et al. used carbene cyclopropanation in several synthetic endeavors. In one example, the diazoketone was treated with bis-A-tert-butylsalicylaldiminato copper(II) [Cu(TBS)2, 388] to induce the carbene cyclopropanation reaction. The diazoketone was prepared by treating 386 with mesyl azide to give 387 in 82% yield, which was followed by treatment with the Cu(TBS)2 reagent to produce 389 in 80% yield in Taber and co-workers synthesis of (-i-)-isoneonepatelactone.308... 

Difficulties have been reported in the chromatographic separation of the desired product from excess 4-toluenesulfonyl azide and 4-toluenesulfonamide (Doyle et al., 1985 Hudlicky et al., 1985). Taber et al. (1986, 1988) found that methanesulfonyl azide (mesyl azide) is generally a superior reagent for diazo transfer. ... 

The advantage of methanesulfonyl azide (mesyl azide) is that it is easily separated from the desired product by washing the organic phase (CH3CN or ether) with 1097o aqueous NaOH solution. Other transfer reagents are either more expensive or show similar disadvantages to those of 4-toluenesulfonyl azide (see Taber et al., 1986, references 5 and 6). Since 1985, Taber (1989) prefers mesyl azide to 4-toluenesulfonyl azide in all diazo transfers. 

When the diazospecies 109, prepared by diazo transfer fron mesyl azide, was treated with Rh2(OAc)4 in benzene under reflux, the two products 110 and 111 were formed in a ratio of 38 62. Use of the corresponding Pmb ether gave only... 

Another advantage of sterically demanding trisyl azide is the selective azidation of cyclic 8-ketoesters (eq 32). Thus, the desired azidation product A was slowly formed as a single product in either THF or MeCN. In contrast, more reactive sulfonyl azides such as 4-methoxybenzenesulfonyl azide, 4-nitrobenzenesulfonyl azide, mesyl azide, triflyl azide, and tosyl azide provided not only the azidation product A but also a ring-contraction product B, a ring-opened diazo-transfer product C, and a mixture of ring-opened olefins D. The amounts of by-products B, C, and D were dependent upon the azide reagent. 

The diazoquinolinediones 22 were synthesized from the corresponding 4-hydroxy-2-quinolones through a diazotransfer reaction with mesyl azide. The rhodium(II) catalyzed Wolff rearrangement of the diones 22 in refluxing acetonitrile afforded oxindole derivatives 23 as a single product. 

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). 

Synthesis of 2-diazo>l,3"dicarbonyl or 2-diazo-3-ketoesters using tosyl azide or mesyl azide. 

A versatile diazotation of enamines 32 with mesyl azide 33 (MsNs) afforded the... 

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