ASYMMETRIC SYNTHESIS OF PROLINE USING COBALT(III)-TETRAAMINE COMPLEXES

Abstract

The decarboxylation reaction of δ -cis-β-[Co(L₁)(pdH)]²⁺ complex yielded δ -cis-β-[Co(L₁) (R-pro)]²⁺, while the δ -cis-β-[Co(L₂) (S-pro)]²⁺ was obtained from the reaction of δ -cis-β-[Co(L₂) (pdH)]²⁺, where L₁ is (3R)3-methyl-1, 6-bis[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, L₂ is (3S) 3-methyl-1, 6-bis-[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, and pdH is the pyrrolidine-2, 2-dicarboxylate ion. The asymmetrically synthesized prolines were isolated via the decomposition of the decarboxylated complexes. The proline isolated from δ -cis-β-[Co(L₁) (R-pro)]²⁺ showed a specific rotation of +12.0, representing a 24% excess of R-proline over S-proline, while the proline isolated from δ -cis-β-[Co(L₂) (S-pro)]²⁺ showed a specific rotation of -10.0, indicating a 20% excess of S-proline over R-proline.     

Carbon-13 NMR analysis of cyclobutane dimers from benzocycloalkenes

¹³C NMR Spectra for a series of 11 substituted cyclobutanes derived from photodimerization of benzocycloalkenes were recorded. Comparison of the carbon chemical shifts for the head-to-head and head-to-tail cis-syn-cis and cis-anti-cis isomers reveals shielding trends which should facilitate structural and stereochemical assignments for related compounds. The head-to-head isomers show a larger separation of cyclobutane carbon resonances than the head-to-tail isomers. The cis-syn-cis isomers relative to the cis-anti-cis isomers exhibit distinctive upfield shifts of all carbon resonances, except those of aromatic carbons ortho to alkyl-substituted aromatic carbons.     

Crystal structures and photoreactivity of trans- and cis-valerophenone diperoxides

Abstract  

The crystal structures of valerophenone diperoxides trans-1 and cis-1 were elucidated by X-ray crystallographic analysis. The 1,2,4,5-tetraoxane rings of both compounds adopt chair conformations. Intermolecular CH···O hydrogen bond, π–π, and CH/π interactions exist in cis-1, whereas only CH/π interactions exist in trans-1. In the asymmetric unit of the crystal, a half molecule exists for trans-1, while one molecule for cis-1 which shows whole-molecule disorder. Solid-state photolysis (at 254 nm) or solution-state thermolysis (at 150 °C) of trans-1 and cis-1 produced valerophenone (2) and butyl benzoate (3). Rationalization of the solid-state photoreactivity of the diperoxides by their crystal structures was attempted.     

Stereoselective epoxidation of 2-arylidene-1-indanones and 2-arylidene-1-benzosuberones

Summary Oxidation of the (E) and (Z) isomers of 2-arylidene-1-indanones (1) and 2-arylidene-1-benzosuberones (4) by alkaline hydrogen peroxide (methodi) afforded the spiroepoxidestrans-2a–g andtrans-5a–g from both isomers as sole products in high yields. On the other hand, dimethyldioxirane epoxidation(methodii) of the (E) isomers1a–g and4a–g gave the correspondingtrans spiroepoxides in good yields, whereas the (Z) isomers1a,c,e and4a,c,e led to thecis spiroepoxides in moderate yields. Dimethyldioxirane oxidation (methodii) of (Z)-1c and (Z)-4c,e gave diones3c and6c,e as by-products as well. Epoxidation of (Z)-1a,c,e and (Z)-4a,c,e bym-chloroperoxybenzoic acid (methodiii) resulted inca. 6:1 mixtures ofcis-2a,c,e andtrans-2a,c,e orcis-5a,c,e andtrans-5a,c,e spiroepoxides.Dedicated to Prof.W. Fleischhacker on the occasion of his 65^th birthday     

Two different crystal and molecular structures for dicarbonyl(η2-cis-cyclooctene)[η6-1,3,5-triethyl-2,4,6-tris-(trimethylsilylmethyl)-benzene]molybdenum(0): a highly crowded but surprisingly stable molecule

Summary Two crystal and molecular structures have been determined for the sterically very crowded molecule dicarbonyl(²-cis-cyclooctene)[⁶-1,3,5-triethyl-2,4,6-tris-(trimethylsilylmethyl)-benzene]-molybdenum(0),3 a und3 b. In structure3 a the crystals are monoclinic, space group P2₁/n, whereas in3 b they are orthorhombic, space group P2₁2₁2₁. In3 a the carbon-carbon double bond of thecis-cyclooctene moiety is almost parallel to the benzene ring plane; in3 b it is inclined at an angle of nearly 15°. In both3 a and3 b the co-ordinatedcis-cyclooctene and arene moieties adopt conformations which are very similar to those calculated to be the ground states of the free molecules.

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Zwei unterschiedliche Kristall- und Molekülstrukturen von Dicarbonyl (²-cis-cycloocten)[⁶-1,3,5-triethyl-2,4,6-tris-(trimethylsilylmethyl)-benzol]molybdän(0): einem hochgespannten aber überraschend stabilen Molekül

Zusammenfassung Von dem sterisch sehr gespannten Molekül Diarbonyl(²-cis-cycloocten)[⁶-1,3,5-triethyl-2,4,6-tris-(trimethylsilylmethyl)-benzol]molybdän(0) wurden zwei unterschiedliche Kristall-und Molekülstrukturen3 a und3 b ermittelt. Die Kristalle von3 a sind monoklin (Raumgruppe P2₁/n), jene von3 b orthorhombisch (Raumgruppe P2₁2₁2₁). In3 a ist die Kohlenstoff-Kohlenstoff Doppelbindung dercis-Cycloocteneinheit nahezu parallel zum Benzolring angeordnet; in3 b ist sie um etwa 15° gekippt. Die Konformationen des koordiniertencis-Cycloocten sowie des Arens sind sehr ähnlich jenen Grundzustandsstrukturen, die für die nichtkoordinierten Moleküle berechnet wurden.

     

Synthese von threo-cis/threo-trans- und erythro-cis/erythro-trans-Dihydropalustrin. 17. Mitteilung über Schachtelhalmalkaloide

Synthesis of threo-cis/threo-trans- and erythro-cis/erythro-trans-dihydropalustrin The first synthesis of a threefold protected spermidine, namely ³-benzyloxycarbonyl-N¹-phthaloyl-N²-tosylspermidin ( 9 ) is presented. Each of the protecting groups can be removed selectively. After hydrazinolysis the resulting N³-benzyloxy-carbonyl-N²-tosylspermidine ( 10 ) has been condensed with methyl (2 E)-cis-7,8-epoxy-2-decenoate to the threo-cis/trans piperidines 17 , and with methyl (2 E)-trans-7,8-epoxy-2-decenoate to the erythro-cis/trans piperidines 17 , respectively. After catalytic removal of the Z group, the resulting aminoesters 13 and 18 , in a melt with imidazole, underwent ring closure to the 13-membered lactames 14 and 19 , respectively. reductive deprotection of the N-tosyl group with sodium/ammonia led to the stereoisomeric palustrines 15 and 20 , respectively.     

Stereochemical aspects of proton chemical shifts. X—The slow exchange 1H NMR spectrum of cis-transoid-cis-perhydroanthracene and of cis-decalin

The slow exchange 360 MHz ¹H NMR spectra of cis-transoid-cis-perhydroanthracene and of cis-decalin have been assigned. Shift increments due to the cis-annelation of a tetramethylene bridge to cyclohexane are presented.     

Pheromone, 1. Mitt.: (+)-cis-Disparlure: Synthese und Feldtests

Summary A synthesis of (+)-cis-disparlure is described starting from racemic 2-hydroxy-dodecannitrile (2), which is transformed into the O-protected enantiomerically pure cyanohydrine4. Grignardreaction followed by reduction with BH₃ · (CH₃)₂S yields the correspondingthreo-configurated secondary alcohol10. After tosylation and cleavage of theMBE-protective-group (+)-cis-disparlure (14) is obtained by treatment with KOH. Mating disruption field tests exhibited a significantly increased effectiveness of (+)-cis-disparlure as compared to the racemic product.

Unserem verehrten Lehrer Professor Dr. O. Hromatka zum 85. Geburtstag gewidmet     

Synthese ceramidähnlicher Verbindungen

Zusammenfassung Bei der Synthese vondl-threo-1-Hydroxy-2-N-lignoceryl-3-O-acetyl-4-cis-octadecen werden folgende Verbindungen erstmalig dargestellt:dl-threo-1,3-Dihydroxy-2-N-lignoceryl-4-cis-octadecen,dl-threo-1-O-Trityl-2-N-lignoceryl-3-hydroxy-4-cis-octadecen unddl-threo-1-O-Trityl-2-N-lignoceryl-3-O-acetyl-4-cis-octadecen. In gleicher Weise wurden die dazu analogen Verbindungen synthetisiert, die durch einen Myristoylrest an Stelle des Lignocerylrestes substituiert sind. Zu Vergleichszwecken wird auch dasdl-threo-1,3-Dihydroxy-2-N-lignoceryl-4-cis-octadecen dargestellt. Die Konstitution der Verbindungen wurde durch die IR-Spektren bestätigt.Mit 1 Abbildung.Prof. Dr. Dr. h. c.Friedrich Wessely-Karnegg zum 70. Geburtstag mit den besten Wünschen.1. Mitt.: Mh. Chem.98, 373 (1967).     

The synthesis,crystal structures and infrared spectra of bis(2,2′-bipyridyl)mononitratozinc(II) hexafluorophosphate and bis(2,2′-bipyridyl)mononitratozinc(II) perchlorate: A comparison with existing [Zn(chelate)2(OXO)][Y] and [Cu(chelate)2(OXO)][Y] complexes of known crystal structure

In order to extend the number of [Zn(chelate)₂(OXO)][Y] complexes, with chelate =2,2″ bipyridyl, 1,10 phenanthroline and 2,2″-bipyridylamine and (OXO)^-=(ONO)^-, (O₂NO)^-, (O₂CCH₂)^- and (O₂CH)^-, the crystal structures and infrared spectra of [Zn(bipy)₂(O₂NO)][PF₆], (9) and [Zn(bipy)₂(O₂NO)][ClO₄], (10) have been determined. Both zinc(II) complexes involve a slightly elongated cis-distorted ZnN₄O₂ chromophore.The slight elongation contrasts with the more significant compressed cis-distorted octahedral CuN₄O₂ chromophore of the corresponding copper(II) structures. The Zn‐O bonds in (9) are 2.186(3) and 2.351(3)Å (ΔO0.165(3)Å), while the corresponding Zn‐O(1) and Zn‐O(2) bonds in (10) are 2.194(2) and 2.355(2)Å (ΔO0.161(2)Å), respectively. The mean Zn‐O bond distance in (9) is 2.269(3) and 2.275(2)Å in (10). Although the significant cis-distortion of the Zn‐O distances is comparable to the analogous Cu‐O distances, the ΔO values are notably smaller. The thermal ellipsoids of (9) and (10), which are slightly asymmetric (ΔO ≈ 0.16Å), are small and isotropic. Such differences reflect the spherical symmetry of the d ¹⁰ zinc(II) configuration relative to the nonspherical symmetry of the d ⁹ copper(II) ion.The ZnN₄O₂ chromophores of (9) and (10) are similar, indicating the isomorphous and isostructural nature of the complexes. Both complexes have a common back-angle or magic angle of α≈117°, in contrast to the bipyam complexes where the back-angle is much less at ≈105°, related to the conformation of the floppier bipyam chelate ligand.     

An Unanticipated Result in the Pd (0) Catalyzed Coupling of Sodium Adenate with cis-4-Acetyloxy- and cis-4-t-Butyldimethylsilyloxy-2-Cyclopentenyl Diethylphosphate

The preparation of adenine regioisomers of (+/-)-cis-4-(TBSO)-and (+/-)-cis-4-(AcO)-2-cyclopentene is described using either Pd(0) coupling (silyl ether 2) or chloride displacement (acetyl chloride 10). An unexpected difference in reactivity between TBS- and Ac-O-protected allyl phosphates 2 and 7 in Pd(0) catalyzed coupling with sodium adenate was observed.     

Benzo- and indoloquinolizines. XII—carbon-13 n.m.r. study of the conformation of the 1,2,3,4,4a,6,7,8,9,13b-decahydro-9a H-pyrido[1,2-f]phenanthridine isomers

The influence of the configuration and the conformation on the ¹³C n.m.r. spectrum of 1,2,3,4,4a,6,7,8,9,13b-decahydro-9aH-pyrido[1,2-f] phenanthridine was investigated. These observations, coupled with the low temperature spectrum allowed us to confirm the trans-syn-cis as the preferred conformation for one of the four isomers. At ?40°C, 2–3% of another conformer could be detected and identified as the cis-anti-cis-2.     

Synthesis and Characterization of One-dimensional Dicyclohexyl-18-crown-6 Complexes with M2[Cd(mnt)2] (M = Na, K)

Two supramolecular crown ether complexes [Na(DC18C6-A)(H₂O)]{[Na(DC18C6-A)][Cd(mnt)₂]} (1) and [K(DC18C6-A)]₂[Cd(mnt)₂] (2) (DC18C6-A = cis-syn-cis-dicyclohexyl-18-crown-6, isomer A; mnt = maleonitriledithiolate) have been synthesized and characterized by elemental analysis, FT-IR spectroscopy and X-ray single crystal diffraction. Complex 1 is composed of one [Na(DC18C6-A)(H₂O)]⁺ complex cation and one {[Na(DC18C6-A)][Cd(mnt)₂]}⁻ complex anion and displays an infinite chain-like structure through N–Na–N interactions. In complex 2, [K(DC18C6-A)]⁺ complex cation and [Cd(mnt)₂]²⁻ complex anion afford a novel 1D ladder-like structure by N–K–N, N–K–S interactions.     

Benzo- and indoloquinolizine derivatives. VI—configuration and conformation of 4b,5,6,7,8,8a,10,11,16,16b-decahydrodibenz[f,h]indolo[2,3-a]quinolizine diastereoisomers. A 270 MHz 1H NMR study

The synthesis of a D/E cis isomer of the title compound is described. In an attempt to obtain the other D/E cis isomer, epimerisation reactions were studied. The configuration and conformation of the isomers are determined on the basis of their ¹H NMR spectra. The shift of the 16b proton on N-9 protonation indicates the quinolizidine conformation. At 270 MHz, the ABCD system of the C-10 and C-11 methylenes can be analysed. The ²J(C-10H₂), together with the multiplicity of H-8a, allows an unequivocal assignment of a cis-anti-cis structure to the only D/E cis isomer obtained.     

Theoretical study of the stereoisomers of tetrahydrocannabinols

A theoretical AM1 semiempirical study of the major active components of marijuana and their stereoisomers is presented. It was found that the calculated partition coefficients, dipole moments, heats of formation, volume, surface area, ovality, and conformation of the pyran ring cannot explain the activity differences between the stereoisomers. The major factor is the orientation of the carbocyclic ring and its C₁ substituent with respect to the phenyl group hydroxyl oxygen. Our study has revealed and supports the involvement of previously described steric features of cannabinoids in determining their biological potency. Based on these conclusions, we predicted the relative activities for the (+)-cis-δ¹-THC, (-)-cis-δ¹-THC, (+)-cis-δ⁶-THC, and (-)-cis-δ⁶-THC stereoisomers, which have not been synthesized. © 1997 John Wiley & Sons, Inc.     

pH-Driven Variation of the Outer-Sphere Binding Mode of cis-[Co(Ad)(en)2Cl]Cl (en-Ethylendiamine, Ad-Adeninate) with p-Sulfonatothiacalix[4]arene

The non-symmetrical cobalt (III) complex cis-[Co(Ad)(en)₂Cl]Cl (1Cl), possessing two flexible ethylendiaminate chelate rings (en) and monodentate N(9)-bound adeninate (Ad^-) was chosen as the guest of p-sulfonatothiacalix[4]arene (STCA) to study the inclusion complex formation at wide range of pH 2–10. It was shown by ¹H, NOE NMR methods and pH-metric procedure, that pH-driven variation of the inclusion mode of 1 ⁺ into calixarene cavity is the result of the protonation of 1 ⁺ via adeninate moiety.     

Low-temperature 15N NMR spectra of reduced 1,3-heterocyclic systems

The ¹⁵N NMR spectra of the O-inside cis-fused conformer of perhydropyrido[1,2-c][1,3]thiazine shows a shielding of the nitrogen of 23.0 ppm relative to the trans-fused conformer. In contrast, ¹⁵N shifts for the cis-and trans-fused conformers of perhydro-oxazolo[3,4-a]pyridine and perhydrothiazolo[3,4-a]pyridine show corresponding shieldings of only 0.6 and 2.5 ppm, respectively.     

2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine: Synthesis,conformation, and conversion to 1-(2-hydroxyethoxy)-2-methoxydiazene-1-oxide. Crystal structure of 1-[2-(para-nitrobenzoyloxy)-ethoxy]-2-methoxydiazene-1-oxide

The oxidation of 1,2-bis(methoxyaminooxy)ethane (3) with PbO₂ afforded 2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine (4) in the form of the 55:45 mixture of thetrans-4ee- andcis-4 isomers. The barrier of the ring conversion (G₂₃₈ =11.3 kcal/mole) of thecis-4 isomer was determined by the method of¹³C NMR. The regio- and stereospecific stereoelectronically controlled reaction of (4) withpara-nitrobenzoic acid gives the equimolar mixture of methylpara-nitrobenzoate and the 1,2-dialkoxydiazene oxide (5), the structure of which, and the (E)-configuration, were shown by the x-ray structural data of its acylation product — the diazene oxide (6).N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2624–2632, November, 1992.     

Brønsted Acid Catalyzed Asymmetric Synthesis of cis-Tetrahydrocannabinoids**

We report herein the catalytic asymmetric cyclization of 1-aryl terpenols to afford enantiomerically highly enriched Δ⁹-cis-tetrahydrocannabinoid scaffolds in a single step. As powerful chiral catalysts strongly acidic imidodiphosphorimidates (IDPis) have been identified which furnish the products with good yields and excellent enantioselectivity. Upon MOM-deprotection some naturally occurring cannabimimetica such as (−)-cis-Δ⁹-tetrahydrocannabinol and (−)-perrottetinene as well as some unnatural analogues were made accessible along a merely 3-step biomimetic sequence (MOM=methoxymethyl).     

A Convenient Synthesis of (-)-Methyl Epijasmonate

A short, enantioselective synthesis of (-)-methyl epi-jasmonate, ent-1, has been achieved starting from readily available Corey lactone aldehyde 9. The key features include the stereoselective installation of 2,3-cis-disubstituted side-chains by hydrogenation of dienoate 8 and subsequent one-carbon degradation.