Highly Regio- and Stereoselective Catalytic Synthesis of Conjugated Dienes and Polyenes (original) (raw)
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Regio- and stereoselective hydrosulfonylation of conjugated dienes via (.pi.-allyl)palladium complex
The Journal of Organic Chemistry, 1983
The combination of a sulfonylpalladation of acyclic dienes 1 (with 2 equiv of NaSOzR and 1 equiv of PdClz in acetic acid or acetic acid-H20 at 50-80 "C under air) and a protiodepalladation of the thus obtained [I-(sulfonylmethy1)-T-allyl]palladium complexes 3 with dimethylglyoxime (in a protic solvent at room temperature) provides di-and trisubstituted (Z)-A3-sulfones 12 selectively, irrespective of the stereochemistry of the starting dienes. Similar treatment of 1-vinylcycloalkenes 5 (n 5 6) provides the stereochemically defined (2-sulfonyl-ethy1idene)cycloalkanes 19, the formal 1,4-addition products of a sulfinic acid to s-cis-5, in high selectivity. The dienes 5 (n = 8 and 10) are transformed to a mixture of 19 and 20. These regio-and stereoselectivities are rationalized uniformly by assuming a hydrolytic cleavage of the (u-ally1)palladium intermediate activated by an A(Is3) strain between Pd and the substituent on the allylic position.
Journal of Organic Chemistry, 2001
Regio-and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic transformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.
Table of contents 1. General experimental information S3 2. Experimental procedures and characterization data S4 a. Synthesis of dienes S4 b. Synthesis of alkyl amides S5 c. General procedure for the Pd-catalyzed preparation of 2-piperidinones S10 d. Mechanistic experiments S27 Reaction with diene (E)-2m and (Z)-2m S27 Isolation of palladacycles S29 Reaction of palladacycles with diene 2a S32 e. Manipulation of the products S33 3. References S36 4. NMR spectral data S37 S3 1. General experimental information Reactions were conducted in dry solvents under Argon unless otherwise stated. Dry solvents were obtained from Acros Organics, Extra Dry over Molecular Sieves, and used without further purification. Pd(OAc)2 (98%) [3375-31-1] was obtained from Strem. All other chemicals were purchased from Sigma-Aldrich, Acros Organics, Alfa Aesar, Fluorochem or Abcr and they were used as received. All palladium-catalyzed reactions were carried without precautions to elude moisture or oxygen. The abbreviation "rt" refers to reactions carried out at a temperature between 21-25 ºC. Reaction mixtures were stirred using Teflon-coated magnetic stir bars. Thin layer chromatography (TLC) was carried out on pre-coated silica gel F254 plates with visualization under UV light or by dipping the plate into solutions of p-anisaldehyde or cerium nitratefollowed by heating. Column chromatography was performed on silica gel (40-60 μm) unless otherwise stated. NMR data was collected on Varian Mercury 300 MHz or Bruker AVIII 500 MHz spectrometers. Chemical shifts are given in ppm (δ) and are referenced to the residual CDCl3 solvent peak at 7.26 ppm (1 H NMR) and 77.16 ppm (13 C NMR). Conventional onedimensional (1D) 1 H NMR, 19 F NMR, 13 C{ 1 H} NMR, Distortionless Enhancement by Polarization Transfer Spectra (DEPT) and two-dimensional (2D) 1 H-1 H Correlation Spectroscopy (COSY), 1 H-1 H Nuclear Overhauser Effect Spectroscopy (NOESY), 1 H-13 C heteronuclear single quantum coherence (HSQC), 1 H-13 C Heteronuclear Multiple-Bond Correlation Spectroscopy (HMBC) experiments were recorded at room temperature under routine conditions. NMR data was analyzed using MestReNova NMR data processing software (http://mestrelab.com/). High Resolution Mass Spectra (HRMS) were performed at the CACTUS facility of the University of Santiago de Compostela on a Bruker micrOTOF spectrometer. X-ray crystallographic analysis of 3af, 4, 5 and 6 was performed at the CACTUS facility of the University of Santiago de Compostela. X-ray crystallographic analysis of 3aa was performed at the CACTI facility of the University of Vigo. S4 2. Experimental procedures and characterization data Synthesis of dienes Dienes 2a ((E)-buta-1,3-dien-1-ylbenzene), 2h (isoprene) and 2l (1,3cyclohexadiene) were commercially available. 2a and 2h were purchased from Aldrich and 2l from Acros Organics. Dienes 2b ((E)-1-(1,3-butadienyl)-4-nitrobenzene), 2c ((E)-1-(1,3-butadienyl)-3-fluorobenzene), 2d ((E)-1-(1,3-butadienyl)-2methoxybenzene), 2e ((E)-deca-1,3-diene), 2i ((E)-(2-methylbuta-1,3-dien-1yl)benzene), 2k (1-vinylcyclohex-1-ene) and (E) and (Z)-2m (tertbutyldimethyl(penta-2,4-dien-1-yloxy)silane) were synthesized from the corresponding aldehyde via Wittig reaction according to the literature. 1 Diene 2g (ethyl (E)-penta-2,4-dienoate) was also synthesized with a method previously reported in literature. 2 Spectral data recorded was in agreement with the previously reported. Diene 2f ((E)-N-methoxy-N-methylhepta-4,6-dienamide) was prepared from the corresponding ester, already prepared in the literature, 3 following the procedure shown below. i PrMgCl (2.0 M in THF, 15 mL, 30 mmol, 4.2 equiv) was added to a suspension of CH3NH(OCH3). HCl (1.46 g, 14.63 mmol, 2 equiv) in THF (71 mL), under Ar atmosphere, at-15 ºC. The resulting mixture was stirred for 20 minutes. Then, the ester (1 g, 7.13 mmol, 1 equiv.) was added and the solution was warmed to 0 °C. The mixture was stirred for 3 h before NH4Cl (sat.) (25 mL) was added to quench the reaction. The layers were separated, and the aqueous layer was extracted with EtOAc (3 × 50 mL). The combined organic layers were washed with brine (50 mL), dried over Na2SO4 and concentrated in vacuo. The crude product was purified by column flash chromatography on silica gel (20 to 60% EtOAc/hexanes) to give the diene 2f as a pale-yellow oil (1.19 g, 99%). 1 H NMR
The Journal of Organic Chemistry, 1993
The palladium-mediated intramolecular dieneto-diene coupling with intramolecular trapping provides a novel route for the stereoselective construction of two new rings via the net 1,Caddition of carbon and oxygen across an internal diene subunit. We recently began a study of the palladium-mediated reactions of certain tetraene compounds, substrates that contain within their structures two 1,3-diene subunits.1-4 Our interest in the cyclization/trapping of these substrates derives from the extensive literature describing efficient palladium-mediated dimerization/trapping reactions of l,&butadiene, a process referred to as butadiene telomeriati ion.^' Our studies are directed toward developing this cyclization strategy for applications in natural product total synthesis, and toward that goal, we are exploring solutions to the problem of controlling reaction mode selectivity and/or group selectivity in the cyclizations of unsymmetric tetraenes. The attempted cyclizationltrapping of the unsymmetric tetraene 1 illustrates the problem. Treating 1 with 0.05 equivof a [Pd(OAc)2/3Ph8] mixture and 2.2 equiv of phenol affords some of the cyclized and phenol-trapped product. The phenoxy moiety adds se