Nitrones computational methods

A contribution to the synthesis of oxoindoles equipped with quaternary stereocenters of high stereochemical purity was made by Smith et al. [15] in 2009. Nitrones 31 derived from Garner s aldehyde cycloadd readily to ketenes 32, a process that intensifies its asymmetric induction with increasing size of the protecting group (PG). An initially proposed ionic addition to the quaternary carbon of the ketene was subsequently mled out through computational methods [16]. The weak N-O... 

The structures of donor-acceptor complexes of iyn-benzoyl azide, its 2-methyl- and 2,6-dimethyl-substituted derivatives with BF3, AICI3, and SbCls, and the transition states of the rearrangement into isocyanates have been reported by computational methods. The reaction of donor-substituted alkenes with a-diazo-a-nitro ethyl acetate under Rh catalysis have been reported which show that the nitro group is inserted forming cyclic nitronates, whereas the ester moiety was not incorporated into the ring system (Scheme 198). ... 

Ono and Kamimura have found a very simple method for the stereo-control of the Michael addition of thiols, selenols, or alcohols. The Michael addition of thiolate anions to nitroalkenes followed by protonation at -78 °C gives anti-(J-nitro sulfides (Eq. 4.8).11 This procedure can be extended to the preparation of a/jti-(3-nitro selenides (Eq. 4.9)12 and a/jti-(3-nitro ethers (Eq. 4.10).13 The addition products of benzyl alcohol are converted into P-amino alcohols with the retention of the configuration, which is a useful method for anri-P-amino alcohols. This is an alternative method of stereoselective nitro-aldol reactions (Section 3.3). The anti selectivity of these reactions is explained on the basis of stereoselective protonation to nitronate anion intermediates. The high stereoselectivity requires heteroatom substituents on the P-position of the nitro group. The computational calculation exhibits that the heteroatom covers one site of the plane of the nitronate anion.14... 

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