Several α-alkylated β-amino esters have been obtained via DKR processes employing a kit of transaminases and isopropylamine as an amino donor in aqueous medium under mild conditions. Thus, while acyclic α-alkyl-β-keto esters afforded excellent conversions and enantioselectivities, although usually low diastereoselectivities, using more constrained cyclic β-keto esters high to excellent inductions were obtained.
Cycloalkyl Substituted Pyrimidinediamine Compounds And Their Uses
申请人:Li Hui
公开号:US20070299060A1
公开(公告)日:2007-12-27
The present disclosure provides 2,4-pyrimidinediamine compounds having antiproliferative activity, compositions comprising the compounds and methods of using the compounds to inhibit cellular proliferation and to treat proliferate diseases such as tumorigenic cancers.
Chemo- and Diastereoselective Reduction of .beta.-Enamino Esters: A Convenient Synthesis of Both cis- and trans-.gamma.-Amino Alcohols and .beta.-Amino Esters
Convenient procedures for the chemo- and diastereoselective reduction of beta-enamino esters 1 are described. Both cis- and trans-gamma-amino alcohols 2 or beta-amino esters 3 can be prepared by reduction of beta-enamino esters 1, readily available starting materials, with the use of inexpensive reagents Nali-PrOH or NaHbB(OAc)(3)/AcOH, respectively, and the appropriate reduction conditions. The mechanisms and diastereoselectivities for the reductions are discussed. The relative configurations and conformations of the diastereoisomeric gamma-amino alcohols 2 and beta-amino esters 3 obtained are established by H-1 and C-13 NMR study and unequivocally set by their cyclic derivatives tetrahydro-1,3-oxazines 4.
New type of cyclization of .alpha.,.beta.,.chi.,.psi.-unsaturated dioic acid esters through tandem conjugate additions by using lithium N-benzyl-N-(trimethylsilyl)amide as a nitrogen nucleophile
作者:Tadao Uyehara、Naomi Shida、Yoshinori Yamamoto
DOI:10.1021/jo00037a034
日期:1992.5
Treatment of dimethyl (2E,6E)-2,6-octadienedioate with lithium N-benzyl-N-(trimethylsilyl)amide (LSA) gave 5-exo-trig ring closure products, methyl 3-(N-benzylamino)-2-(methoxycarbonyl)cyclopentane-1-acetates, through tandem conjugate additions. The related 6-exo-trig cyclization proceeded stereoselectively to give ethyl c-3-(N-benzylamino)-t-2-(ethoxycarbonyl)cyclohexane-1-acetate. In contrast with the 5- and 6-exo-trig cyclization, no 7-exo-trig cyclization occurred. The 5-exo-trig cyclization products were converted into 2-(methoxycarbonyl)-2-cyclopentene-1-carboxylic acid methyl ester in an excellent yield. 5-exo-trig cyclization of the unsymmetrical dienedioate consisting of crotonate and (E)-2-methyl-2-butenoate units proceeded regioselectively through conjugate addition of LSA to the crotonate part. Similar regioselectively was observed in the case of 5-exo-trig cyclization of the dienedioate possessing crotonate and (E)-3-methyl-2-pentenoate units. Total syntheses of the physiologically active cyclopentane monoterpenes (+/-)-dihydronepetalactone and (+/-)-isohydronepetalactone has been accomplished by this cyclization strategy. In addition, it has been demonstrated that LSA is a more efficient nitrogen nucleophile than LDA to cyclize omega-halo-alpha,beta-unsaturated esters.