Epoxide and Aziridine Ring Opening

which was the result of addition to the least substituted position. A -Acyl aziri-dines do not afford addition products with amines, but undergo rearrangement to form oxazolines 115 [57]. 

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Roche G2 (1999, 2004) plan for oseltamivir phosphate epoxide ring opening (step 8), aziridine formation (step 9), and aziridine ring opening (step 10). 

Various epoxides and aziridines undergo smooth ring opening with water in presence of bismuth triflate (10 mol%) to provide the corresponding v/c-diols and p-amino alcohols with excellent regioselectivity [35]. Reaction of styrene oxide with water in the presence of Bi(OTf)3 affords styrene 1,2-diols (Fig. 7). Similarly,... 

Catalytic ring opening of epoxides and aziridines was also observed (Eq. 27). The acetone cyanohydrine reaction provided j8-hydroxy nitrile and / -amino nitriles, with the lanthanide isopropoxides exhibiting a higher reactivity than Et3N [233]. 

Copper-catalyzed asymmetric allylic alkylations with organometalUc reagents used for small-ring openings, such as epoxides and aziridines, have gained interest. Illustrating... 

Lanthanide isopropoxides were introduced as the first-generation alkoxide-type precatalysts (Structures 1-3) [133]. They proved to be more effective in the catalytic ring-opening of epoxides and aziridines than Et3N [134]. The acetone cyanohydrin reaction provided 5-hydroxynitriles and /3-aminonitriles. Strong basicity of the lanthanide isopropoxides is considered to catalyze the transhydrocya-nation effectively from acetone cyanohydrin to several aldehydes and ketones [135]. YbBu3 exhibited similar catalytic activity in this reaction. 

Jacobsen reported in 1990 that Mnm complexes of chiral salen ligands (41) were the most efficient catalysts available for the enantioselective epoxidation of alkyl- and aryl-substituted olefins.118 This stimulated a rapid development in the chemistry and applications of chiral SB complexes, which offer promising catalytic applications to several organic reactions, such as enantioselective cyclopropanation of styrenes, asymmetric aziridination of olefins, asymmetric Diels-Alder cycloaddition, and enantioselective ring opening of epoxides.4,119... 

Carboxylic acids are well known nucleophiles for opening epoxides and aziridines. Recently the stereoselective epoxide ring opening has also been achieved via palladium catalyzed formal 1,4 addition <05TL7243>. 

Indoles react with epoxides and aziridines in the presence of Lewis acids (see 20.4.1 for reaction of indolyl anions with such reactants) with opening of the three-membered ring and consequent 3-(2-hydroxyethylation) and 3-(2-aminoethylation) of the heterocycle. Both ytterbium triflate and phenylboronic acid are good catalysts for reaction with epoxides under high pressure silica gel is also an effective catalyst, but reactions are slow at normal pressure and temperature. Reaction with aziridines can be catalysed by zinc triflate or boron trifluoride. °... 

Ring cleavage. Catalyzed hy Sc(OTf)3, alcoholysis of epoxides and aziridines proceeds at room temperature. The ring opening of mei oepoxides is rendered asymmetric if a chiral ligand such as 1 is added to the reaction medium. Lactones give polymers via alcoholysis. ... 

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