THE DIELS-ALDER ADDUCT OF NORBORNADIENE AND CYCLOPENTADIENE [CONTRIBUTION FROM THE DEPARTMENT O F CHEMISTRY, STATE UNIVERSITY OF IOWA] Tetracyclic Dienes. I. The Diels-Alder Adduct of Norbornadiene Cyclopentadiene (original) (raw)
ChemInform Abstract: Cyclocondensations of Homophthalic Anhydrides with 1-Aza-1,3-dienes
ChemInform, 1995
a,B-Unsaturated aldimines (1-aza-l,3-butadienes) 2, 4 and 7a-d react with homophthalic anhydrides la, b to give 3,4-dihydro-l(2H)-naphthalenone-4-carboxylic acids 3, 5, 8a-d (R 2 = H) as main products. Homophthalic anhydride la and cJnnamal~aline 7d gave rise to the diastereoisomeric naphthalenones 8d (R 2 = H), along with the 3,4-dihydro-l(2H)-isoquinolinone-4-carboxylic acids 10 (R ~ = H), and 3,4-dihydro-l(2H)-pyridinone 11 (R 2 = H) as products of 3,4-, 1,2-and 1,4-addition to the 1-aza-l,3-butadiene, respectively. The effect of the reaction conditions on the ratio of adducts, produced by la and 7d, was studied. The structure and relative configurations of 3, 5, $a-d, 10 and 11 were determined by NMR spectroscopy. In the case of cis-naphthalenone 8¢ and dihydropyridinone 11, the structure was confirmed by X-ray crystal structure analysis.
Helvetica Chimica Acta, 1981
The preparations of 1-acetylvinyl arenecarboxylates H2C=C (COCH,)OCOR with R = phenyl, p-nitrophenyl, 2,4-dinitrophenyl, u-and P-naphthyl are described (3). The Diels-A Ider reactivity of these dienophiles toward cyclopentadiene is evaluated and compared with that of methyl vinylketone, 3-trimethylsilyloxy-, 3-ethoxy-and 3-acetoxy-3-buten-2-ones. The stereoselectivity of the cycloadditions of these dienophiles with 2,3,5,6-tetramethylidene-7-oxanorbornane (1) and 5,sdimethoxy-l,4-epoxy-2,3-dimethylidene-I, 2,3,4-tetrahydroanthracene (2) is studied. In principle, the dienophiles 3 allow direct functionalization of the position C(9) of the A-ring of daunomycinone analogs by Diels-Alder additions to exocyclic dienes such as 1 and 2. Introduction.-Anthracyclinones are aglycones of very important antibiotics and anti-tumor drugs [l]. They can be prepared readily [2] [3] by two successive 3a-i R' 1 2a R1=R2=OCH3 R = a Me3Si f 2,4-(NO2)2-C6H3CO h RI=R2=H b Et g a-naphthyl-CO c R1=OCH3, R2=H c CH3CO h 8-naphthyl-CO d C~H S C O i CH3 e 4-(N02)-C6HdCO j H Diels-Alder additions [4] to 2,3,5,6-tetramethylidene-7-oxanorbornane (1) [5]. The A-ring of daunomycinone (4) [6] bears a hydroxy group at C(9), adjacent to the carbonyl function of the side-chain. This OH group can be introduced, in principle I)
Cyclocondensations of homophthalic anhydrides with 1-aza-1,3-dienes
Tetrahedron, 1995
a,B-Unsaturated aldimines (1-aza-l,3-butadienes) 2, 4 and 7a-d react with homophthalic anhydrides la, b to give 3,4-dihydro-l(2H)-naphthalenone-4-carboxylic acids 3, 5, 8a-d (R 2 = H) as main products. Homophthalic anhydride la and cJnnamal~aline 7d gave rise to the diastereoisomeric naphthalenones 8d (R 2 = H), along with the 3,4-dihydro-l(2H)-isoquinolinone-4-carboxylic acids 10 (R ~ = H), and 3,4-dihydro-l(2H)-pyridinone 11 (R 2 = H) as products of 3,4-, 1,2-and 1,4-addition to the 1-aza-l,3-butadiene, respectively. The effect of the reaction conditions on the ratio of adducts, produced by la and 7d, was studied. The structure and relative configurations of 3, 5, $a-d, 10 and 11 were determined by NMR spectroscopy. In the case of cis-naphthalenone 8¢ and dihydropyridinone 11, the structure was confirmed by X-ray crystal structure analysis.
Journal of Chemical Research, 2009
2,3,4a,6,8a-Penta-acetoxy decahydronaphthalene has been synthesised starting from 1,2,3,4-tetrahydronaphthalen-2-ol. The Birch reduction of 1,2,3,4-tetrahydronaphthalen-2-ol gave a high yield of 1,2,3,4,5,8-hexahydronaphthalen-2-ol which was acetylated. The OsO4 oxidation of the 1,2,3,4,5,8-hexahydronaphthalen-2-yl acetate followed by further acetylation gave the pentaacetates.
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
Chemistry - A European Journal, 1997
2-Methyl-I ,3-dimorpholino-l,3butadiene 1 reacted with a,a-unsaturated Fischer carbene complexes to give a wide range of different products depending on the substitution pattern. Thus, sevenmembcred rings (4, 5 and 6) could be obtained from chromium complexes 2 with aromatic or vinylic groups at the /I position. Similar results were observed when a-methyl-substituted carbene complex 7 a was used. Six-membered carbocycles (derivatives of cycloadducts 12 and 13) were isolated after reaction with both chromium and tungsten complexes bear-ing one or two alkyl groups at the /3 position (10 and 11). Moreover, cyclopentenones 20 were the main products when the starting carbene complexes were alkylsubstituted at both CI and /3 positions (19a, b) or when aromatic (19c,d) instead of vinylic complexes were used. A bicy-Keywords C-H activationcarbene complexes -