A three-pot
asymmetric synthesis of the anti-1,3-diol
unit was developed. In the first pot, enantioselective aldol reaction
of aldehydes proceeds, catalyzed by organocatalyst, followed by either
Wittig or Horner–Wadsworth–Emmons reactions to afford
δ-hydroxy α,β-unsaturated carbonyls with excellent
enantioselectivity. Diastereoselective hydroxy-directed anti-epoxidation proceeds in the next pot by the use of tert-BuOOH and LiHMDS. Reductive opening of the epoxide proceeds in a
third pot to afford anti-β,δ-hydroxy
carbonyl compounds with excellent diastereo- and enantioselectivity.
The asymmetric cross-aldol reaction of two different aldehydes is a synthetically relevant reaction. Diarylprolinol catalyst with trifluoromethyl substituents and sulfonamide catalyst derived from diphenylprolinol are organocatalysts for the crossaldol reaction. The reactivity and stereoselectivity of these two catalysts were compared in the asymmetric cross-aldol reactions of propanal and acetaldehyde as nucleophilic aldehydes and several electrophilic aldehydes. Depending on the electrophilic aldehydes, the preferable catalyst differs. By the proper selection of these two catalysts, potentially synthetically useful chiral building blocks can be synthesized with diastereoselectivities of anti: syn = 2.6:1 ~> 20:1 and enantioselectivities of 60 > 98% ee.
The asymmetric Michael reaction of malononitrile and α,β-unsaturated aldehydes catalyzed by diarylprolinol silyl ether was developed. Michael products were obtained in good yield and with excellent enantioselectivity without formation of overreaction products. As a malononitrile moiety can be transformed into alkoxy or amino carbonyl moieties by oxidative transformation, an α-chiral ester or amide with an all-carbon quaternary center can be synthesized with excellent enantioselectivity.
An asymmetric domino Michael/Michael reaction of α,β‐unsaturated aldehydes 1 and α‐acetyl‐β‐substituted‐α,β‐unsaturated esters 2 catalyzed by diphenylprolinol silyl ether was developed. This is a formal carbo [4+2] cycloaddition reaction affording penta‐substituted cyclohexanes having the three continuous chiral centers with excellent diastereo‐ and enantioselectivity.
A large-scale materials database including literature and factual data, which is under construction at the Institute for Materials Research, Tohoku University is introduced featuring the collections of ternary amorphous formation phase diagrams. The database is arranged as a multimedia type, including both text and images, which is especially important in materials research. The object-oriented method is also applied to construct the database so it can predict new compositions to form an amorphous phase from existing data.
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