Azides alkene reactions

The preparation and immediate use of manganese(III) azide species generated slowly in situ by refluxing manganese(III) acetate and sodium azide in acetic acid in presence of alkene reaction substrates to prepare 1,2-diazidoalkanes avoids the need to isolate manganese(III) azide which has a high probability of explosive instability [1]. The (II) azide is known [20260-90-6], isolable, detonable and has been patented as a power source for lasers [2],... 

Vogel and Delavier (26) reported a synthesis of the 6-azabicyclo[3.2.2]nonane skeleton 130 using an intramolecular azide-alkene cycloaddition strategy (Scheme 9.26). When refluxed in xylene, the azide 126 underwent an intramolecular 1,3-dipolar cycloaddition with the internal alkene. Nitrogen extrusion and subsequent rearrangement led to a mixmre of compounds 128, 129, and 130. Reactions of azides with the double bond of dienes were also used in various total syntheses of alkaloids, and will be discussed later in Section 9.2.2. 

Schkeryantz and Pearson (59) reported a total synthesis of ( )-crinane (298) using an intramolecular azide-alkene cycloaddition (Scheme 9.59). The allylic acetate 294 was first subjected to an Ireland-Claisen rearrangement followed by reduction to give alcohol 295, which was then converted into the azide 296 using Mitsunobu conditions. Intramolecular cycloaddition of the azide 296 in refluxing toluene followed by extrusion of nitrogen gave the imine 297 in quantitative yield. On reduction with sodium cyanoborohydride and subsequent reaction with... 

Iron(n) salts mediated the coupling of trialkylboranes with KSGN to give RSCN via a radical process.553,554 Stereochemically pure ( )-l-thiocyanato-alkenes or ( )-l-azide-alkenes were obtained from alkynes when hydro-boration with disiamylborane was followed by reaction with potassium thiocyanate or sodium azide in the presence of copper(n) nitrate, copper(n) acetate, and small amount of water in polar aprotic solvent (Equation (116)).555... 

Logothetis studied the thermal intramolecular azide-alkene cycloaddition (IAAC) of 5-azido-5-methyl-1-hexene and observed the formation of a mixture of imines and aziridines <65JA749>. The first case of utilization of silica gel in the selective decomposition of triazoline (35) to pyridines and aziridines (X = CH2—CH2, (CH2)3) was reported by Murthy and Hassner (Equation (17)) <87TL97>. The role of silica gel in the chemoselective reaction is still obscure, but it is likely that acidic surface... 

Fig. 10.13. Hammett plots of cycloaddition rates of substituted aryl azides with nucleophiUc, electrophilic, and unsubstituted alkenes showing the ambiphilic character of the azide cycloaddition. Reaction with maleic anhydride (electrophilic) is favored by donor substituents. Reaction with pyrroUdinocy-clohexene (nucleophilic) is favored by acceptor substituents.

Ciufolini and co-workers demonstrated the use of 1,3-dipolar azide-olefin cycloaddition reactions in the total synthesis of ( )-FR66979 (52) [25], an antitiunor agent which is structurally related to the mitomycins [26]. Thus, the triazoline 50 was obtained as a single diastereomer by smooth cycloaddition of the activated double bond and the dipole in 49 by heating in toluene. Brief photolysis of 50 provided aziridine 51, which fragmented to 52 (Scheme 8B). Other intramolecular azide-alkene cycloaddition in natural product synthesis is illustrated by a munber of examples [27-32]. 

Hassner and co-workers have shown that the intramolecular azide-alkene cycloaddition reactions of azido vinyl j8-lactams primarily lead to cis fused triazolines. The triazoline 61, fused to a 6-membered ring, was formed exclusively as the cis-fused isomer and decomposed on treatment with silica gel to imine 66. On the other hand, the 8-membered ring fused triazoline 63 which was isolated as a cis trans mixture, on exposme to sUica, produced only aziri-... 

Azides are very versatile and valuable synthetic intermediates, known for their wide variety of applications, and have been employed for the synthesis of a number of important heterocyclic compounds. Azides also represent a prominent class of 1,3-dipoles, and their cycloaddition to multiple tt-bonds is an old and widely used reaction (1988CR297). The dipolar cycloaddition of an azide to an alkene furnishes a triazoline derivative (2003MI623). Azide-alkene cycloadducts can extrude nitrogen at elevated temperatures to form aziridines or imines, depending upon the substrate and reaction conditions. The cycloaddition of azides with alkynes affords triazolidine derivatives which have been a focus in the area of chemical biology and have received much recent attention (2008AGE2596, 2008CR2952). In this section of our review, we recount some developments of the 1,3-dipolar cycloaddition reaction of azides that have been used for the synthesis of various alkaloids. 

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