Synthesis of a 16-Membered Cyclic Peptide Model of the BCF Rings of Ristocetin A Using Arene-Ruthenium Chemistry Coupled with Cycloamidation
摘要:
A convergent synthetic approach to the cyclic peptide 4, which is a model for the B/C/F ring system of ristocetin B, is described. A key reaction is the coupling of the phenolic dipeptide 5, constructed from arylglycine subunits, with the chlorophenylalanine-RuCp cationic complex 6, followed by demetalation of the product to give the diaryl ether 7, without epimerization at any of the amino acid residues. Deprotection of 7 followed by cycloamidation affords the target molecule 4, produced as a mixture of atropdiastereomers which were separated and characterized by NMR spectroscopy.
Organocatalyzed Formal [4+2] Cycloaddition of<i>in situ</i>Generated Azoalkenes with Arylacetic Acids: An Efficient Approach to the Synthesis of 4,5-Dihydropyridazin-3(2<i>H</i>)-ones
作者:Xuanyi Li、Kuo Gai、Zhenbo Yuan、Jie Wu、Aijun Lin、Hequan Yao
DOI:10.1002/adsc.201500645
日期:2015.11.16
An unprecedented [4+2] cycloaddition of in situ generated azoalkenes with arylaceticacids has been developed under the catalysis of isothiourea. The reaction provided an efficientapproach to the synthesis of 4,5-dihydropyridazin-3(2H)-one derivatives in moderate to good yields (up to 95%).
Diastereoselective Aza‐Mislow–Evans Rearrangement of
<i>N</i>
‐Acyl
<i>tert</i>
‐Butanesulfinamides into α‐Sulfenyloxy Carboxamides
作者:Fan Tang、Yun Yao、Yan‐Jun Xu、Chong‐Dao Lu
DOI:10.1002/anie.201809551
日期:2018.11.19
diastereoselective [2,3] rearrangement of O‐silyl N‐sulfinyl N,O‐ketene acetals derived from chiral N‐acyl tert‐butanesulfinamides was developed, giving α‐sulfenyloxy carboxamides with excellent enantioselectivity. Enolization and subsequent silylation of N‐acyl tert‐butanesulfinamides initiate this aza variant of the Mislow–Evans rearrangement, in which the chirality at the sulfur atom in the rearrangement precursors
Organocatalytic Michael addition–lactonisation of carboxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents
作者:Louis C. Morrill、Daniel G. Stark、James E. Taylor、Siobhan R. Smith、James A. Squires、Agathe C. A. D'Hollander、Carmen Simal、Peter Shapland、Timothy J. C. O'Riordan、Andrew D. Smith
DOI:10.1039/c4ob01788a
日期:——
Isothiourea HBTM-2.1 catalyses the Michael addition–lactonisation of 2-aryl and 2-alkenylacetic acids and α,β-unsaturated trichloromethyl ketones. Ring-opening of the resulting dihydropyranones and subsequent alcoholysis of the CCl3 ketone with an excess of methanol gives a range of diesters in high diastereo- and enantioselectivity (up to 95 : 5 dr and >99% ee). Sequential addition of two different
Dihydropyridones: Catalytic Asymmetric Synthesis, N- to C-Sulfonyl Transfer, and Derivatizations
作者:Carmen Simal、Tomas Lebl、Alexandra M. Z. Slawin、Andrew D. Smith
DOI:10.1002/anie.201109061
日期:2012.4.10
promotes the reaction of ammonium enolates derived from arylacetic acids with N‐tosyl‐α,β‐unsaturated ketimines, thus giving dihydropyridones with high diastereo‐ and enantiocontrol (see scheme). These products readily undergo N‐ to C‐sulfonyl photoisomerization and are derivatized to afford stereodefined piperidines and tetrahydropyrans.
Process for selective synthesis of enantiomers of substituted 1-(2-amino-1-phenyl-ethyl)-cyclohexanols
申请人:Mahaney Erin Paige
公开号:US20070135449A1
公开(公告)日:2007-06-14
A process for the enantioselective synthesis of an (S)— or (R)-1-[2-dimethylamino)-1-(methoxyphenyl)ethyl]cyclohexanol and analogues or salt thereof are described. The method involves the steps of (a) reacting an (S) or (R) 4-benzyloxazolidinone with a mixed anhydride of a methyoxyphenylacetic acid under conditions which form a oxazolidinone, (4S)— or (4R)-4-benzyl-3-[methyoxyphenyl]acetyl]-oxazolidin-2-one, (b) treating the (4S)— or (4R)-4-benzyl-3-[(methoxyphenyl)acetyl]-1,3-oxazolidin-2-one with an aprotic amine base and titanium chloride in a chlorinated solvent under conditions which permit formation of the corresponding anion, (c) mixing the corresponding anion with titanium chloride and cylcohexanone under conditions which permit an aldol reaction to form the corresponding (4S)— or (4R)-4-benzyl-3-[(2R)-2-(1-hydroxycyclohexyl)-2-(methoxyphenyl)acetyl]-1,3-oxazolidin-2-one, (d) hydrolyzing the (4S)— or (4R)-4-benzyl-3-[(2R)-2-(1-hydroxycyclohexyl)-2-(methoxyphenyl)acetyl]-1,3-oxazolidin-2-one to form a chiral acid (2S or 2R)-(1-hydroxycyclohexyl)-methoxyphenyl)acetic acid, (e) coupling the chiral phenylacid to a secondary amine to form an amide, and (f) reducing the amide to form an (S) or (R) 1[2-dimethylamino)-1-(methoxyphenyl)ethyl]cyclohexanol or a salt thereof.