title: Nanocrystalline MgO for asymmetric Henry and Michael reactions.
abstract: Nanomaterials with their three-dimensional structure and defined size and shape are considered to be suitable candidates for proper alignment with prochiral substrates for unidirectional introduction of reacting species to induce an asymmetric center. We herein report the design and development of a truly recyclable heterogeneous catalyst, nanocrystalline magnesium oxide, for the asymmetric Henry reaction (AH) to afford chiral nitro alcohols with excellent yields and good to excellent enantioselectivities (ee's) for the first time. Bronsted hydroxyls are the sole contributors for the ee, while they add on to the activity in AH. It is demonstrated that the hydrogen bond interactions between the -OH groups of (S)-(-)-binol and the -OH groups of MgO are essential for the induction of enantioselectivity. Further, to prove the above hypothesis, we have successfully carried out another reaction, asymmetric Michael reaction (AM) with nanocrystalline MgO. The reusable and suitably aligned nanocrystalline MgO-catalyzed AH and AM reactions afforded chiral products with comparable ee's to that of the homogeneous system.
authors.affiliation: Ogene Systems (I) Private Limited, Hyderabad, India. bmchoudary@yahoo.com
authors.forename: Boyapati M
authors.initials: BM
authors.lastname: Choudary
authors.forename: Kalluri V S
authors.initials: KV
authors.lastname: Ranganath
authors.forename: Ujjwal
authors.initials: U
authors.lastname: Pal
authors.forename: Mannepalli L
authors.initials: ML
authors.lastname: Kantam
authors.forename: Bojja
authors.initials: B
authors.lastname: Sreedhar
mesh_terms: D002384:Catalysis; D003460:Crystallization; D008024:Ligands; D008277:Magnesium Oxide / Q000737:chemistry*; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D009573:Nitrites / Q000138:chemical synthesis* / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D008024:Ligands; D009573:Nitrites; D009942:Organometallic Compounds; D008277:Magnesium Oxide; C037538:methyl nitrite