Application of High Pressure Induced by Water-Freezing to the Direct Catalytic Asymmetric Three-Component List−Barbas−Mannich Reaction
摘要:
High pressure induced by water-freezing has been successfully applied to the direct catalytic asymmetric-three component List-Barbas-Mannich reaction, in which higher yield and better enantioselectivity can be realized than those from the reaction at room temperature under 0.1 MPa.
Enantioselective Total Synthesis of Brevetoxin A: Convergent Coupling Strategy and Completion
作者:Michael T. Crimmins、J. Lucas Zuccarello、Patrick J. McDougall、J. Michael Ellis
DOI:10.1002/chem.200900777
日期:2009.9.14
A highly convergent, enantioselective totalsynthesis of brevetoxin A is reported. The development of a [X+2+X] Horner–Wadsworth–Emmons/cyclodehydration/reductive etherification convergent couplingstrategy allowed a unified approach to the synthesis of two advanced tetracyclic fragments from four cyclic ether subunits. The Horner–Wittig coupling of the two tetracyclic fragments provided substrates
Highly stereoselective N-acyliminium ion coupling reactions of β-ketoester derived silyl enol ethers with enantiopure lactams derived from (S)-malic acid are reported. This reaction type is applied in the synthesis of the enantiopure C-2 substituted lactam 27, a plausible intermediate in a projected synthesis of ptilomycalin A.
Diastereoselectivity in the Carroll rearrangement of β-keto esters of tertiary allylic alcohols
作者:Michael E. Jung、Brian A. Duclos
DOI:10.1016/j.tetlet.2003.10.102
日期:2004.1
Carroll rearrangement of β-keto esters derived from tertiary allylic alcohols, for example, 7, under basic conditions followed by decarboxylation of the resulting β-keto acids yielded the expected γ,δ-unsaturated methyl ketones 8 with a range of olefin geometries from 100:0 to 1:1.8 E/Z, depending on the relative steric requirements of the two groups at the allylic center.
在碱性条件下,衍生自叔烯丙醇的β-酮酯(例如7)的Carroll重排,然后将所得的β-酮酸脱羧,得到预期的γ,δ-不饱和甲基酮8,其烯烃几何结构范围为100 :0到1:1.8 E / Z,取决于在烯丙基中心的两组的相对空间要求。
[EN] LIGANDS<br/>[FR] LIGANDS
申请人:JOHNSON MATTHEY PLC
公开号:WO2004111065A1
公开(公告)日:2004-12-23
A substituted paracyclophane is described of formula (I) wherein Xl and X2 are linking groups comprising between 2 to 4 carbon atoms, Y1 and Y2 are selected from the group consisting of hydrogen, halide, oxygen, nitrogen, alkyl, cycloalkyl , aryl or heteroaryl, Z1, Z2 and Z3 are substituting groups that optionally contain functional groups, a, b, c, d, e and f are 0 or l and a + b + c + d + e + f = 1 to 6. PreferablyX1 and X2 are -(C2H4)- and a + b + c + d + e + f = 1 or 2. The substituted paracyclophane provides transition metal catalysts that demonstrate high activity and selectivity for asymmetric reactions.
描述了一种具有以下式(I)的取代对环戊烷,其中X1和X2是包含2到4个碳原子的连接基团,Y1和Y2选自氢、卤素、氧、氮、烷基、环烷基、芳基或杂环芳基,Z1、Z2和Z3是可选地含有官能团的取代基团,a、b、c、d、e和f为0或1,且a + b + c + d + e + f = 1到6。最好X1和X2为-(C2H4)-,且a + b + c + d + e + f = 1或2。这种取代对环戊烷提供了过渡金属催化剂,表现出对不对称反应具有高活性和选择性。
The totalsynthesis of a new member of the pederin family of natural products, psymberin 1, was accomplished. Using a recently reported novel and efficient PhI(OAc)2 mediated oxidative entry to 2-(N-acylaminal)-substituted tetrahydropyrans as the key step, this totalsynthesis was executed in a convergent and efficient manner. The longest linear sequence of this synthesis was 22 steps starting from