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Aziridine nucleophilic opening

With Oxygen Nucleophiles Aziridine ring-opening of 111 (Scheme 3.42) with water in the presence of a catalytic amount of TsOH gave the corresponding (3-hydrox-yphenylalanine derivative 121 in 72% yield as the major isomer [74], Treatment of N-(p-tolylsulfmyl) aziridine-2-carboxylates with TFA and subsequent aqueous workup resulted in the formation of j3-substituted serine derivatives [62, 63, 101]. Under these reaction conditions, not only was the aziridine ring opened, but also the N-sulfmyl group was removed treatment of 122 (Scheme 3.43) with TFA at 73 °C, for example, afforded 123 in 75% yield [101],... [Pg.90]

An indirect nucleophilic opening is depicted in Scheme 24. The functionalized vinyl aziridine 37 undergoes a Michael-initiated ring closure (MIRC) reaction upon treatment with suitable nucleophiles to give cyclopropanes with concomitant opening of the aziridine ring [34]. [Pg.107]

Miiller and Nury examined aziridine ring opening using Grignard reagents as nucleophiles. They found that the reaction proceeds in moderate selectivities in the presence of copper catalysts such as 69 ... [Pg.283]

Aziridines may be prepared by the intramolecular nucleophilic opening of epoxides by amines and their derivatives (84CAR(130)103,92T5639,92TL487,92TL5351) (Scheme 15). [Pg.517]

The synthesis of substituted cysteines can be accomplished via Michael addition reactions,]67124-126] by nucleophilic displacement,]127] from racemic thiazolines,]128] via aziridine ring opening,]129 and by asymmetric synthesis using a chiral auxiliary.]130] The details for some of these methods are described. [Pg.43]

Nitrogen-based nucleophiles continue to remain popular in ring-opening reactions of aziridines. a-Substituted-a-methoxycarbonyl-V-nosylaziridines were opened with a variety of functionalized amines to provide access to enantiopure a,a -disubstituted (3-lactam scaffolds for ditopic peptidomimetics <07OL101>. A related intramolecular regioselective 3,Y-aziridine ring opening with an a-amino functionality was reported in the synthesis of... [Pg.67]

Type I aziridines can be prepared via photolysis of functionalized pyridinium ions. Mariano and co-workers have shown that irradiation of pyridinium ion 40 via a 450 W Hanovia lamp with Vycor filter will induce a ring contraction to produce a fused-bicyclic aziridine moiety 41 (Equation 16) <1996JOC4439>. The azabicyclo[3.1.0]hexane prepared through this method can rapidly experience nucleophilic opening to produce an amine-substituted cyclo-pentene. [Pg.114]

Table 6 Aziridine ring openings with suifur nucleophiles... Table 6 Aziridine ring openings with suifur nucleophiles...
Nitriles can act as nitrogen nucleophiles in aziridine ring-opening reactions. Two examples are shown in Scheme 25 in which a formal [3-1-2] cycloadduct is the final product. Tosylaziridine 147 was reacted with benzoni-trile and BF3 OEt2 catalysis to produce the r-fused imidazoline 148 <2004TL1137>. The utility of the reaction is limited in the case of cyclic aziridines to benzofused aziridines and either aryl or benzyl nitriles. It was also found that the reaction required stoichiometric BF3. Lesser amounts of Lewis acid reduced the chemical yield drastically. [Pg.135]

Aziridines react with nucleophiles other than carbon nucleophiles. In the presence of TBAF, trimethylsilyl azide react with V-tosylaziridines to give the azido A-tosylamine. A-Benzylic aziridines are opened by trimethylsilyl azide in the presence of a chromium catalyst. Acetic anhydride reacts with N-tosylaziridines, in the presence of PBU3, to give the A-tosylamino acetate. A-Tosylaziridines react with InCls to give the chloro A-tosylamine. ... [Pg.621]

The opening of halocyclopropanes to allyl systems according to equation 124 can happen thermally or with the assistance of electrophiles and nucleophiles . Some recent examples include an efficient cyclopentenone synthesis (equation 125) ", an electrocyclic opening/cyclization sequence giving functionalized furan and pyran derivatives (equation 126), an elegant total synthesis of the very fast death factor alkaloid ( ) anatoxin and a nice application of the well known nucleophilic opening to the preparation of crystalline methylene aziridines (equation 127) . [Pg.412]

Intramolecular 1,3-dipolar cycloaddition of azide (81) proceeds through a triazoline and vinyl-aziridine (82) and results in the formation of tetrahydropyrrolizidine (83) and (84). This represents a formal total synthesis of supinidine. Thermolysis of vinyl aziridine (82) leads to pyrrolizidine (84) probably via azomethine ylides, while the nucleophilic opening leads exclusively to (83) through an intermediate allylic iodide (85). The latter is produced as a mixture of (E) and (Z) isomers but is converted to (83) via an equilibrium and recyclization of the (Z)-isomer (Scheme 30) <85TL3523, 85TL3527). [Pg.83]


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See also in sourсe #XX -- [ Pg.201 , Pg.202 ]

See also in sourсe #XX -- [ Pg.201 , Pg.202 ]




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Aziridine ring opening with nucleophiles

Aziridines ring opening with nucleophiles

Nucleophiles opening

Nucleophiles opening aziridines

Nucleophilic Opening of Aziridines

Nucleophilic Ring Opening of Aziridines and Related Reactions

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