Radical addition to oxime ethers for asymmetric synthesis of beta-amino acid derivatives

The diastereoselective alkyl radical addition to chiral oxime ethers was studied with a view to preparing enantiomerically pure alpha,beta-dialkyl-beta-amino acid derivatives. The phase transfer-catalyzed alkylation of Oppolzer's camphorsultam derivative of oxime ether proceeded smoothly to give the alkylated N-(beta-oximino)acyl derivatives. In the presence of BF3.OEt2, radical addition to the oxime ethers proceeded using triethylborane as the radical initiator to give alpha,beta-dialkyl-beta-amino acid derivatives with excellent diastereoselectivity.     

Structure and magnetic property of bimetallic hexanuclear cluster based on 5-chlorosalicylaldehyde oxime

The bimetallic hexanuclear cluster [Mn4Ni2O2（Cl-Sao）6.（CH3OH）8].10CH3OH （1） was synthesized. Single-crystal X-ray analysis reveals that 1 consists of two [Mn2Ni（μ3-O）（Cl-Sao）3] subunits linked together via two pairs of long Ni-O bonds involving two oximate oxygen atoms and two phenolate oxygen atoms. Each Mn and Ni center achieves six-coordination with axial methanol molecules. The spin centers of the Mnm and Niu ions exchange magnetic coupling through O2-, O-phenolate and -N-O- bridges. The magnetic properties of the cluster have been investigated.     

Esters of jasmorange oxime

The aldehyde jasmorange (1) was converted to the oxime (2), acylation of which by alkylcarboxylic acid anhydrides in the presence of HClO₄ or by acid chlorides in the presence of pyridine synthesized esters of jasmorange oxime 3–24 in 82–91% yields. Refluxing 3–24 in hexane converted them quantitatively into nitrile 25. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 307–310, July–August, 2007.     

Excellent diastereoselective allylation of camphor derived glyoxylic oxime ethers mediated by a Lewis acid

The nucleophilic allylation of camphor derived glyoxylic oxime ethers was carried out using allyltributyltin in the presence of Sn(OTf)₂ affording the corresponding homoallylic amines in high chemical yields (up to 94%) and excellent stereoselectivities (up to >99%).     

红霉素A9-（1-异丙氧基环已基）肟的合成及其晶体结构

合成表征了红霉素A9-（1-异丙氧基环已基）肟的E和Z异构体，并在丙酮-水混 合溶液中培养出了前者的单晶，X射线衍射表明，其结构为正交晶系，P2_12_12_1 空间群，晶胞参数：a=2.3101(5) nm, b=2.3761(5) nm, c=0.97066(19)nm, V=5. 3279(8) nm~3，Z=4，μ=0.088 mm~(-1)，F(000)=2064, D_c=1.176 g/cm~3。E-红 霉素A 9-（1-异丙氧基环已基）肟的晶体结构图明显表明1-异丙氧基环已基保护基 确实使十四元大环的构象发生了扭曲，使6-OH的周围空间不再拥挤，从而导致6- OH甲基化的选择性提高。