RESUMO
Correction for 'Studies towards asymmetric synthesis of 4(S)-11-dihydroxydocosahexaenoic acid (diHDHA) featuring cross-coupling of chiral stannane under mild conditions' by Rui Wang et al., Org. Biomol. Chem., 2015, DOI: 10.1039/c4ob02324b.
RESUMO
An efficient and asymmetric synthetic approach towards one of the biologically interesting 4(S)-11-diHDHA derivatives was developed. This process mainly relied on two reactions, one is the copper-catalyzed mild cross-coupling that allows for the efficient construction of a chiral α-alkynyl α-hydroxy motif and another is the synthesis of chiral α-hydroxy α-stannanes that has previously been developed by our group featuring the asymmetric stannylation using the well-established tributyltin hydride/diethyl zinc system from an aldehyde.
Assuntos
Ácidos Docosa-Hexaenoicos/síntese química , Compostos de Estanho/química , Compostos de Estanho/síntese química , Ácidos Docosa-Hexaenoicos/química , Estrutura MolecularRESUMO
A stereocontrolled synthesis of α-amino-α'-alkoxy ketones is described. This pH-neutral copper(I) thiophene-2-carboxylate (CuTC)-catalyzed cross-coupling of amino acid thiol esters and chiral nonracemic α-alkoxyalkylstannanes gives α-amino-α'-alkoxy ketones in good to excellent yields with complete retention of configuration at the α-amino- and α-alkoxy-substituted stereocenters.
Assuntos
Cobre/química , Cetonas/síntese química , Compostos Orgânicos de Estanho/química , Peptídeos/química , Aminoácidos , Ácidos Carboxílicos , Catálise , Ésteres , Concentração de Íons de Hidrogênio , Cetonas/química , Estrutura Molecular , Estereoisomerismo , Compostos de Sulfidrila/química , Tiofenos/químicaRESUMO
Racemic and scalemic α-(acyloxy)-tri-n-butylstannanes undergo Pd-catalyzed cross-couplings with alkenyl/aryl/heteroaryl iodides, bromides, and triflates in moderate to good yields in THF at 45 °C. Simple aryl iodides and unprotected aza-arenes, two classes of electrophiles that typically react sluggishly, are also good substrates. Cross-couplings proceed with retention of configuration at the alkenyl and stannyl-substituted stereocenters.
Assuntos
Hidrocarbonetos Bromados/química , Hidrocarbonetos Iodados/química , Paládio/química , Compostos de Trialquitina/química , Alcenos/química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
Prochiral ketones are reduced to enantioenriched, secondary alcohols using catecholborane and a family of air-stable, bifunctional thiourea-amine organocatalysts. Asymmetric induction is proposed to arise from the in situ complexation between the borane and chiral thiourea-amine organocatalyst resulting in a stereochemically biased boronate-amine complex. The hydride in the complex is endowed with enhanced nucleophilicity while the thiourea concomitantly embraces and activates the carbonyl.
Assuntos
Aminas/química , Reagentes de Ligações Cruzadas/química , Cetonas/química , Tioureia/química , Catálise , Oxirredução , Estereoisomerismo , Especificidade por SubstratoRESUMO
Scalemic alpha-cyanohydrin triflates undergo Pd-catalyzed cross-coupling with aryl, heteroaryl, and vinyl boronic acids under mild conditions. Coupling proceeds with complete inversion of configuration at the stereogenic carbon. The resultant nitrile can be easily converted into a variety of alternative functional groups of value in organic synthesis and thus achieves a higher level of molecular complexity than the products of traditional Suzuki reactions.
Assuntos
Nitrilas/química , Catálise , Paládio/química , EstereoisomerismoRESUMO
A facile, one-pot reaction cascade condenses 1,1,1-trichloroalkanes with alpha,beta-unsaturated ketones to unexpectedly furnish moderate to good yields of (E)-2-alkylidenecyclobutanols.
Assuntos
Ciclobutanos/química , Ciclobutanos/síntese química , Cetonas/química , EstereoisomerismoRESUMO
Cross metathesis of the acrolein-derived phosphono allylic carbonate and hydroxy alkenes using second generation Grubbs catalyst and copper(I) iodide gave the substituted phosphonates in good yield. Stereospecific palladium(0)-catalyzed cyclization gave tetrahydrofuran and tetrahydropyran vinyl phosphonates. Regioselective Wacker oxidation of the vinyl phosphonate gave the beta-keto phosphonate, which underwent HWE reaction with benzaldehyde to yield the unsaturated ketone. The utility of the cross metathesis/cyclization protocol was further demonstrated by a formal synthesis of centrolobine.
Assuntos
Álcoois/química , Alcenos/síntese química , Compostos Alílicos/síntese química , Carbonatos/síntese química , Éteres Cíclicos/síntese química , Compostos Organofosforados/síntese química , Alcenos/química , Compostos Alílicos/química , Carbonatos/química , Catálise , Ciclização , Éteres Cíclicos/química , Cetonas , Estrutura Molecular , Compostos Organofosforados/química , Paládio , EstereoisomerismoRESUMO
Treatment of cyclic tert-trihalomethylcarbinols with CrCl(2) in THF/HMPA in the presence of aryl or aliphatic aldehydes initiates a cascade sequence of one carbon ring expansion-olefination affording conjugated exocyclic ketones. Acyclic tert-trihalomethylcarbinols undergo a comparable cascade of one carbon homologation-olefination.
Assuntos
Aldeídos/química , Metanol/química , CiclizaçãoRESUMO
Allylic hydroxy phosphonates and their derivatives can be interconverted by using cross metathesis with second generation Grubbs catalyst. The absolute stereochemistry of the starting phosphonate is conserved in the product. Cross metathesis reaction of the acrolein-derived phosphonate 2a yields a series of functionalized allylic hydroxy phosphonates. However, the cross metathesis reaction is often accompanied by competing dimerization and alkene migration reactions leading to a reduction in yield. The cinnamaldehyde- and crotonaldehyde-derived phosphonates 2b and 2c were also examined. In general, the metathesis reactions of phosphonates 2b and 2c are considerably slower than those for phosphonate 2a leading to mixtures. Several hydroxyl-protected derivatives of the phosphonate 2a (methyl carbonate 3a, acetate 4a, N-tosyl carbamate 5a, TBDMS 6a, and acetoacetate 7a) undergo metathesis without competing side reactions to give substituted allylic phosphonates in good to excellent yield.