Borohydride reduction of acetophenone and esters of dehydrocarboxylic acids in the presence of chiral cobalt(<Emphasis Type="SmallCaps">II</Emphasis>) diamine complexes

The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl₂·L₂ (L₂ are chiral C ₂-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–347, February, 2005.     

A Convenient Stereoselective Synthesis of (1R,2S,3R,4S)-3-(Neopentyloxy)isoborneol

A convenient preparation of (1R,2S,3R,4S)-3-(neopentyloxy)isoborneol (= (1R,2S,3R,4S)-3-(2,2-dimethyl-propoxy)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol; 1a ), a valuable chiral auxiliary, is described. The synthesis involves six steps starting from the readily available camphorquinone ( 5 ) and gives 1a in 48% overall yield. The key step is the chemoselective hydrolysis of the less hindered 1,3-dioxolane moiety in the camphorquinone di-acetal 4 .     

Herstellung enantiomerenreiner Derivate von 3-Amino- und 3-Mercaptobuttersäure durch SN2-Ringöffnung des β-Lactons und eines 1,3-Dixoanons aus der 3-Hydroxybuttersä ure

Preparation of Enantiomerically Pure Derivatives of 3-Amino- and 3-Mercaptobutanoic Acid by S_N2 Ring Opening of the β-Lactone and a 1,3-Dioxanone Derived from 3-Hydroxybutanoic Acid From (S)-4-methyloxetan-2-one ( 1 ), the β-butyrolactone readily available from the biopolymer ( R )-polyhydroxybutyrate (PHB) and various C, N, O and S nucleophiles, the following compounds are prepared:(s)-2-hydroxy-4-octanone ( 3 ), (R)-3-aminobutanoic acid ( 7 ) and its N-benzyl derivative 5 , (R)-3-azidobutanoic acid ( 6 ) (R)-3-mercaptobutanoic acid ( 10 ), (R)-3-(phenylthio)butanoic acid ( 8 ) and its sulfoxide 9 . The (6R)-2,6-dimethyl-2-ethoxy-1,3-dioxan-4-one ( 4 ) from (R)-3-hydroxybutanoic acid undergoes S^N2 ring opening with benzylamine to give the N-benzyl derivative (ent- 5 ) of (S)-3-aminobutanoic acid in 30?40% yield.     

Asymmetrische Michael-Additionen. Stereoselektive Alkylierung chiraler,nicht racemischer Enolate durch Nitroolefine. Herstellung enantiomerenreiner γ-Aminobuttersäure- und Bernsteinsäure-Derivate

Asymmetric Michael-Additions. Stereoselective Alkylation of Chiral, Non-racemic Enolates by Nitroolefins. Preparation of Enantiomerically Pure γ-Aminobutyric and Succinic Acid Derivatives Chiral, non-racemic lithium enolates ( E , F , G ) of 1,3-dioxolan-4-ones, methyl 1,3-oxazolidin-4-carboxylates, methyl 1,3-oxazolin-4-carboxylates, 1,3-oxazolidin-5-ones, and 1,3-imidazolidin-4-ones derived from (S)-lactic acid ( 2a ), (S)-mandelic acid ( 2b ), and (S)-malic acid ( 2c ), or from (S)-alanine ( 10 ), (S)-proline ( 11 ), (S)-serine ( 12 ), and (S)-threonine ( 13 ), are added to nitroolefins. Michael adducts ( 3 – 9 , 14 – 18 ) are formed (40–80%) with selectivities generally above 90% ds of one of the four possible stereoisomers. Conversions of these nitroalkylated products furnish the α-branched α-hydroxysuccinic acids 28 and 29 , the α-hydroxy-γ-amino acid 25 , the α,γ-di-amino acid 32 , the substituted γ-lactames 19 – 22 , and the pyrrolidine 23 . The relative and absolute configuration of the products from dioxolanones and nitropropene are derived by chemical correlation and NOE measurements indicating that the steric course of reaction is to be specified as 1k, ul-1,3. The mechanism is discussed.     

Regioselective Short Synthesis of Epiisoborneol Neopentyl Ether as Chiral Auxiliary: An Absolute Configuration Reset

The regio-selective four step synthesis of (1S,2R,3S,4R)-4,7,7-trimethyl-3-(neopentyloxy)bicyclo[2.2.1]heptan-2-ol, as recognized efficient chiral auxiliary, is presented. The strategy based on opening of the key acetal 15 (=(2S,3aR,4S,7R,7aS)-2-tert-butyl-4,8,8-trimethylhexahydro-2H-4,7-methano-1,3-benzodioxole) thus circumvents the poor reactivity of the neopentyl electrophile under alkylation conditions. Following the same strategy, but using the unreported acetal 22 (=(2R,3aS,4S,7R,7aR)-2-tert-butyl-4,8,8-trimethylhexahydro-2H-4,7-methano-1,3-benzodioxole), the corresponding unreported bis-endo alcohol 23 (=(1R,2R,3S,4S)-3-(2,2-dimethylpropoxy)-4,7,7-trimethylbicyclo[2.2.1]heptan-2-ol) could be isolated only in poor yield. An alternative regioselective synthesis, including an ultimate endo-reduction remains to be found. Several erroneous chiroptical properties from the literature are corrected.     

Novel cembranolides (Coralloidolide D and E) and a 3,7-Cyclized cembranolide (Coralloidolide C) from the mediterranean coral Alcyonium coralloides

The Mediterranean alcyonacean Alcyonium (= Parerytkropodium) coralhides (PALLAS, 1766) is shown to contain three novel diterpenes which are of biogenetic significance: the 3,7-cyclized cembranoid Coralloidolide C ( = (+)-(6R*, 7R*, 11S*, 12aS* 3aE)-7,8-epoxy-3,5,6,7,8,9,10,11,12,12a-decahydro-12a-hydroxy-11-isopropenyl-1,4-dimethyl-3-oxocyciopentacydoundecene-8,6-carbolactone; (?)- 3 ), the O-bridged diketonic cembranolide Coralloidolide D (= (+)-(1R*, 2S*, 3R*, 5R*, 12S*, 8Z)-2,5-epoxy-1-hydroxy-12-isopropenyl-5,9-dimethyl-7,10-dioxocyclotetradeca-8-ene-1,3-carbolactone; (+)- 4 ), and the diketonic epoxycembranolide coralloidolide E (=(+)-(1R*, 2R*, 3R*, 12S*, 5Z, 8Z)-1,2-epoxy-12-isopropenyl-5,9-dimethyl-7,10-dioxocyclotetra-deca-5,8-diene-1,3-carbolactone; (+)- 5 ), The latter in pyridine at r. t. undergoes a double bond shift from C(4) = C(5) to C(4) = C(18) to give the isomer (?)- 7 . Structural assignments are mainly based on ID and 2D NMR and MS spectral data. Either corailoidolide A ((?)- 1 ) or the hypothetic unsaturated 1,4-diketone 9 can be envisaged as the precursors of all coralloidolides.     

Einfache Umwandlung von(–)-(R)-3-Hydroxybuttersäure in das (+)-(S)-Enantiomere und dessen Lacton(‒)-(S)-4-Methyloxetan-2-on

Simple Conversion of (R)-3-Hydroxybutanoic Acid to the (S)-Enantiomer and its Lactone (–)-(S)-4-Methylixetan-2-one Condensation of ( R )-3-hydroxybutanoic acid (1) with ethyl orthoacetate gives a 2-ethoxy-substituted (1,3)dioxanone 2 which is thermally labile: at ca. 100°, two competing processes commence, one leading to ethyl ( R )-3-acetoxybutanoate ( 3 ), the other one - with complete inversion of configuration - to the ( S )-4-methylixetan-2-one ( 4 ) and ethyl acetate. These can be readily separated by fractional distillation. Thus, enantiomerically pure ( S )-3-hydroxybutanoic acid (ent- 1 ) and l-2-alkyl-3-hydroxybutanoic-acid derivatives (such as 6 and 8 ) become available from the biopolymer PHB, the precursor to the acid 1 .     

Synthesis and Stereochemistry of (1S,3S,4S,7R11R)-3-(4-Nitrophenyl)-11-aza-2,6-dioxatricyclo[5,3,1,04,11]undecane

The reaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with glutaraldehyde has been studied. It has been established on the basis of AM1 and PM3 calculations and ¹H NMR spectra recorded in the presence of the shift reagent Eu(fod)₃ that (1S,3S,4S,7R,11R)-3-(4-nitrophenyl)-11-aza-2,6-dioxatricyclo[5,3,1,0^4,11]undecane is formed as the result of the reaction.     

Total synthesis of 2-(β-D-ribofuranosyl)thiazole-4-carboxamide (Tiazofurin) and of precursors of ribo-C-nucleosides

(1R,2S,4R)-2-Cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl (1S′)-camphanate ( 5 ) was transformed into (?)-methyl 2,5-anhydro-3,4,6-O-tris[(tert-butyl)dimethylsilyl]-D -allonate ( 2 ), (+)-1,3-diphenyl-2-{2′,3′,5′-O-tris[(tert-butyl)dimethylsilyl]-β-D -ribofuranosyl}imidazolidine ( 3 ), and the benzamide 20 of 1-amino-2,5-anhydro-1-deoxy-3,4,6-O-tris-[((tert-butyl)dimethylsily)]-D -allitol. Compound 2 was converted efficiently into optically active tiazofurin ( 1 ).     

The Diastereoselective Formation of 1,2,4-Trioxanes and 1,3-Dioxolanes by the reaction of endoperoxides with chiral cyclohexanones

1,4-Diphenyl-2,3-dioxabicyclo[2.2.1]hept-5-ene ( 2 ), on treatment with a catalytic amount of trimethylsilyl trifluoromethanesulfonate (Me₃SiOTf) in CH₂Cl₂ at ?78°, reacts with excess (?)-menthone ( 10 ) to give (1S,2S,4′aS,5R,7′aS)-4′a,7′a-dihydro-2-isopropyl-5-methyl-6′,7′-diphenylspiro[cyclohexane-1,3′-[7′H]cyclopenta-[1,2,4]trioxine] ( 11 ) and its (1R,2S,4′aR,5R,7′aR)-diastereoisomer 12 in a 1:1 ratio and in 21% yield. Repeating the reaction with 1.1 equiv. of Me₃SiOTf with respect to 2 affords 11 , 12 , and (1S,2S,3′a.R,5R,6′aS)-3′a,6′a-dihydro-2-isopropyl-5-methyl-3′a-phenoxy-5′-phenylspiro[cyclohexane-l,2′-[4′H]cyclopenta[1,3]dioxole] ( 13 ) together with its(1R,2S,3′aS,5R,6′aR)-diastereoisomer 14 in a ratio of 3:3:3:1 and in 56% yield. (+)-Nopinone( 15 ) in excess reacts with 2 in the presence of 1.1 equiv. of Me₃SiOTf to give a pair of 1,2,4-trioxanes ( 16 and 17 ) analogous to 11 and 12 , and a pair of 1,3-dioxolanes ( 18 and 19 ) analogous to 13 and 14 , in a ratio of 8:2:3:3 and in 85% yield. (?)-Carvone and racemic 2-(tert-butyl)cyclohexanone under the same conditions behave like 15 and deliver pairs of diastereoisomeric trioxanes and dioxolanes. In general, catalytic amounts of Me₃SiOTf give rise to trioxanes, whereas 1.5 equiv. overwhelmingly engender dioxolanes. Adamantan-2-one combines with 2 giving only (4′aRS,7′aRS)-4′a,7′a-dihydro-6′.7′a-diphenylspiro[adamantane-2,3′-[7′H]cyclopenta[1,2,4]trioxine] in 98% yield regardless of the amount of Me3SiOTf used. The reaction of 1,4-dipheny 1-2,3-dioxabicyclo[2.2.2]oct-5-ene ( 32 ) with 10 and 1.1 equiv. of Me3SiOTf produces only the pair of trioxanes 33 and 34 homologous to 11 and 12 . Treatment of the (S,S)-diastereoisomer 33 with Zn and AcOH furnishes (1S,2S)-1,4-diphenylcyclohex-3-ene-1,2-diol. The crystal structures of 11 – 13 and 16 are obtained by X-ray analysis. The reaction courses of 10 and the other chiral cyclohexanones with prochiral endoperoxides 2 and 32 to give trioxanes are rationalized in terms of the respective enantiomeric silylperoxy cations which are completely differentiated by the si and re faces of the ketone function. The origin of the 1,3-dioxolanes is ascribed to 1,2 rearrangement of the corresponding trioxanes, which occurs with retention of configuration of the angular substituent.     

New synthesis of 4-(1-adamantyl)-2-aryl-1,3-thiazoles from 4-(1-adamantyl)-1,2,3-thiadiazole

Treatment of 4-(1-adamantyl)-1,2,3-thiadiazole with potassium tert-butoxide generated potassium 2-(1-adamantyl)ethynethiolate which reacted with aromatic carboxylic acid chlorides to give unstable S-[2-(1-adamantyl)ethynyl] arenecarbothioates whose acid hydrolysis afforded S-[2-(1-adamantyl)-2-oxoethyl] arenecarbothioates. The latter reacted with ammonium acetate in acetic acid yielding 4-(1-adamantyl)-2-aryl-1,3-thiadiazoles. Reactions of 4-(1-adamantyl)-2-(4-chloro-3-nitrophenyl)-1,3-thiadiazole with cyclic secondary amines gave the corresponding products of nucleophilic replacement of the chlorine atom in the aromatic ring.     

1,3‐Oxathiolanes from the Reaction of Aromatic and Enolized Thioketones with Monosubstituted Oxiranes

The reactions of 4,4′‐dimethoxythiobenzophenone ( 1 ) with (S)‐2‐methyloxirane ((S)‐ 2 ) and (R)‐2‐phenyloxirane ((R)‐ 6 ) in the presence of a Lewis acid such as BF₃?Et₂O, ZnCl₂, or SiO₂ in dry CH₂Cl₂ led to the corresponding 1 : 1 adducts, i.e., 1,3‐oxathiolanes (S)‐ 3 with Me at C(5), and (S)‐ 7 and (R)‐ 8 with Ph at C(4) and C(5), respectively. A 1 : 2 adduct, 1,3,6‐dioxathiocane (4S,8S)‐ 4 and 1,3‐dioxolane (S)‐ 9 , respectively, were formed as minor products (Schemes 3 and 5, Tables 1 and 2). Treatment of the 1 : 1 adduct (S)‐ 3 with (S)‐ 2 and BF₃?Et₂O gave the 1 : 2 adduct (4S,8S)‐ 4 (Scheme 4). In the case of the enolized thioketone 1,3‐diphenylprop‐1‐ene‐2‐thiol ( 10 ) with (S)‐ 2 and (R)‐ 6 in the presence of SiO₂, the enesulfanyl alcohols (1′Z,2S)‐ 11 and (1′E,2S)‐ 11 , and (1′Z,2S)‐ 13 , (1′E,2S)‐ 13 , (1′Z,1R)‐ 15 , and (1′E,1R)‐ 15 , respectively, as well as a 1,3‐oxathiolane (S)‐ 14 were formed (Schemes 6 and 8). In the presence of HCl, the enesulfanyl alcohols (1′Z,2S)‐ 11 , (1′Z,2S)‐ 13 , (1′E,2S)‐ 13 , (1′Z,1R)‐ 15 , and (1′E,1R)‐ 15 cyclize to give the corresponding 1,3‐oxathiolanes (S)‐ 12 , (S)‐ 14 , and (R)‐ 16 , respectively (Schemes 7, 9, and 10). The structures of (1′E,2S)‐ 11 , (S)‐ 12 , and (S)‐ 14 were confirmed by X‐ray crystallography (Figs. 1–3). These results show that 1,3‐oxathiolanes can be prepared directly via the Lewis acid‐catalyzed reactions of oxiranes with non‐enolizable thioketones, and also in two steps with enolized thioketones. The nucleophilic attack of the thiocarbonyl or enesulfanyl S‐atom at the Lewis acid‐complexed oxirane ring proceeds with high regio‐ and stereoselectivity via an S_n 2‐type mechanism.     

乳酸类合成子构建的四连接螺旋手性配位聚合物的合成、结构和光催化性质

通过乳酸衍生物和3-溴-4-羟基苯甲酸的组合得到对映体3-溴-4-(((1R)-1-羧基乙基)氧基)苯甲酸(R-H₂bba)和3-溴-4-(((1S)-1-羧基乙基)氧基)苯甲酸(S-H₂bba)。以其为手性合成子在水热条件下分别与1,3-二(吡啶-4-基)丙烷(1,3-dpp)和Ni²⁺反应,构建了对映手性配位聚合物{[Ni(R-bba)(1,3-dpp)(H₂O)_0.5]·1.5H₂O}_n(HU12-R)和{[Ni(S-bba)(1,3-dpp)(H₂O)_0.5]·1.5H₂O}_n(HU12-S)。结构分析揭示HU12-R和HU12-S是具有dia网络特征的三维螺旋骨架。在骨架中,阴离子配体R-bba^2-和S-bba^2-分别与Ni²⁺中心连接在一起围绕2,螺旋轴得到一对小的对映螺...     

乳酸类合成子构建的四连接螺旋手性配位聚合物的合成、结构和光催化性质

通过乳酸衍生物和3-溴-4-羟基苯甲酸的组合得到对映体3-溴-4-(((1R)-1-羧基乙基)氧基)苯甲酸(R-H₂bba)和3-溴-4-(((1S)-1-羧基乙基)氧基)苯甲酸(S-H₂bba)。以其为手性合成子在水热条件下分别与1,3-二(吡啶-4-基)丙烷(1,3-dpp)和Ni²⁺反应,构建了对映手性配位聚合物{[Ni(R-bba)(1,3-dpp)(H₂O)_0.5]·1.5H₂O}_n (HU12-R)和{[Ni(S-bba)(1,3-dpp)(H₂O)_0.5]·1.5H₂O}_n (HU12-S)。结构分析揭示HU12-R和HU12-S是具有dia网络特征的三维螺旋骨架。在骨架中,阴离子配体R-bba^2-和S-bba^2-分别与Ni²⁺中心连接在一起围绕2₁螺旋轴得到一对小的对映螺旋链,而1,3-dpp与Ni²⁺中心则围绕4₁螺旋轴构建出另外一对大的对映螺旋链。电化学测试显示HU12-R属n型半导体,具有低阻抗性质,对紫外可见光有很强的吸收能力。进一步光催化实验证实在紫外光照射下所得配合物对染料降解有明显催化效果。     

Enantioselektive Reaktionen an porphinoiden Nickelkomplexen

Enantioselective Reactions on Porphine Type Nickel Complexes The thermodynamically controlled addition of alcohols to (+)-(1R)-[1-methyl-8H-HDP]nickelperchlorate ( 1 ; e.e. 92%) yields exclusively the corresponding cis-1,11-disubstituted porphinoids. Chemical transformation of functional groups in the alkoxy side-chain of the chiral addition product followed by acid catalyzed elimination yields the derived alcohols and 1 . By this procedure, the following enantioselective transformations were studied: methylation of meso-2,3-butandiol ( 5 ) to (+)-(2R,3S)-3-methoxy-2-butanol ( 8a ; e.e. 87%), diimide reduction of 2-ethylallyl alcohol ( 9 ) to (+)-(2R)-2-methyl-1-butanol ( 12a ; e.e. 15%), and hydride reduction of 4-hydroxy-2-butanone ( 13 ) to (+)-(3S)-1,3-butandiol ( 16a ; e.e. 20%). Addition of 2,2-dimethyl-1,3-propandiol ( 17 ) to 4 , followed by esterification of the free hydroxy group with trifluoromethanesulfonic anhydride and solvolysis of the sulfonate 19 yielded a bridged complex with unrearranged alkyl chain for which structure 20 is proposed.     

Chirale Synthesebausteine durch Kolbe-Elektrolyse enantiomerenreiner β-Hydroxy-carbonsäurederivate. (R)- und (S)-Methyl-sowie (R)-Trifluormethyl-γ-butyrolactone und -δ-valerolactone

Chiral Building Blocks for Syntheses by Kolbe Electrolysis of Enantiomerically Pure β-Hydroxybutyric-Acid Derivatives. (R)- and (S)-Methyl-, and (R)-Trifluoromethyl-γ-butyrolactones, and -δ-valerolactones The coupling of chiral, non-racemic R* groups by Kolbe electrolysis of carboxylic acids R*COOH is used to prepare compounds with a 1.4- and 1.5-distance of the functional groups. The suitably protected β-hydroxycarboxylic acids (R)- or (S)-3-hydroxybutyric acid, (R)-4,4,4-trifluoro-3-hydroxybutyric acid (as acetates; see 1 – 6 ), and (S)-malic acid (as (2S,5S)-2-(tert-butyl)-5-oxo-1,3-dioxolan-4-acetic acid; see 7 ) are decarboxylatively dimerized or ‘codimerized’ with 2-methylpropanoic acid, with 4-(formylamino)butyric acid, and with monomethyl malonate and succinate. The products formed are derivatives of (R,R)-1,1,1,6,6,6-hexafluoro-2,5-hexanediol (see 8 ), of (R)-5,5,5-trifluoro-4-hydroxypentanoic acid (see 9,10 ), of (R)- and (S)-5-hydroxyhexanoic acid (see 11 ) and its trifluoro analogue (see 12, 13 ), of (S)-2-hydroxy- and (S,S)-2,5-dihydroxyadipic acid (see 23, 20 ), of (S)-2-hydroxy-4-methylpentanoic acid (‘OH-leucine’, see 21 ), and of (S)-2-hydroxy-6-aminohexanoic acid (‘OH-lysine’, see 22 ). Some of these products are further converted to CH₃- or CF₃-substituted γ- and δ-lactones of (R)- or (S)-configuration ( 14 , 16 – 19 ), or to an enantiomerically pure derivative of (R)-1-hydroxy-2-oxocyclopentane-1-carboxylic acid (see 24 ). Possible uses of these new chiral building blocks for the synthesis of natural products and their CF₃ analogues (brefeldin, sulcatol, zearalenone) are discussed. The olfactory properties of (R)- and (S)-δ-caprolactone ( 18 ) are compared with those of (R)-6,6,6-trifluoro-δ-caprolactone ( 19 ).     

New Lignan,Benzofuran, and Sesquiterpene Derivatives from the Roots of Leontopodium alpinum and L. leontopodioides

Three new compounds, including a benzofuran, 1‐{(2R*,3S*)‐3‐(β‐D ‐glucopyranosyloxy)‐2,3‐dihydro‐2‐[1‐(hydroxymethyl)vinyl]‐1‐benzofuran‐5‐yl}ethanone ( 1 ), a lignan, [(2S,3R,4R)‐4‐(3,4‐dimethoxybenzyl)‐2‐(3,4‐dimethoxyphenyl)tetrahydrofuran‐3‐yl]methyl (2E)‐2‐methylbut‐2‐enoate ( 2 ), and a silphiperfolene‐type sesquiterpene, [(1S,2Z,3aS,5aS,6R,8aR)‐1,3a,4,5,5a,6,7,8‐octahydro‐1,3a,6‐trimethylcyclopenta[c]pentalen‐2‐yl]methyl acetate ( 3 ), together with the known coumarins obliquin ( 4 ) and its 5‐methoxy derivative 5 were isolated from the roots of Leontopodium alpinum. Another known coumarin derivative, 5‐hydroxyobliquin ( 6 ), was isolated from the roots of L. leontopodioides. The structures of these compounds were established by spectroscopic studies.     

Synthèse énantiospécifique du (−)-(1R, 3R, 5S)-diméthyl-1,3-dioxa-2,9-bicyclo[3.3.1]nonane

Enantiospecific Synthesis of (?)-(1R, 3R, 5S)-1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane The isomer (?)-(1R, 3R, 5S)-endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane ((1R, 3R, 5S)- 8 ) has been synthesized from (?)-(3R)-methyl 3-hydroxybutanoate. The key intermediate (3R, 5R)- 5 is proved to be a useful synthon for EPC syntheses.     

SYNTHESIS OF ANELLATED ANHYDROPYRANOSES ON THE BASIS OF 1,6-ANHYDRO-3-DEOXY-4-METHYLSULFANYL-3-[(METHYLSULFANYL)METHYLENE]-β-D-ERYTHRO-HEXOPYRANOS-2-ULOSE

(Z)-1,6-Anhydro-3-deoxy-4-methylsulfanyl-3-[(methylsulfanyl)methylene]-β-D-erythro-hexopyranos-2-ulose (1) reacted with diethyl malonate, 1,3-diketones, N-aryl-3-oxobutyramides and dialkyl 3-oxoglutarate, respectively, in the presence of potassium carbonate and crown ether to yield diethyl 2-(1,6-anhydro-4-methylsulfanyl—D-arabino-hex-2-ulopyranos-3-ylmethylene) malonate (2), 1-{(1R,2S,8S,9R)-2-hydroxy-4-methyl-8-methylthio-3,11,12- trioxatricyclo7.2.1.0^2,7dodeca-4,6-dien-5-yl} ethanone (3), (1R,2S,12S,13R)-2-hydroxy-12-methylthio-3,15,16-trioxatetracyclo[11.2.1. 0^2,11. 0^4,9] hexadeca- 4(9),10-dien-8-one (4), (1R,8S,9R)-5-acetyl-3-aryl-8-methylthio-11,12-dioxa- 3-azatricyclo-[7.2.1.0^2,7]dodeca-2(7),5-dien-4-ones (5,6) and dialkyl (1R,8S,-9R)-4-hydroxy-8-methylthio-11,12-dioxatricyclo[7.2.1.0^2,7]dodeca-2(7),3,5-triene-3,5-dicarboxylates (7,8), respectively.     

Co<Superscript>II</Superscript> and Rh<Superscript>I</Superscript> complexes with <Emphasis Type="Italic">C</Emphasis><Subscript>2</Subscript>-symmetric chiral diamines of the dioxolane series

The reaction of di-μ-chlorobis(1,5-cyclooctadiene)dirhodium with (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane (1) gave the complex [Rh(cod)(1)]Cl (cod is 1,5-cyclooctadiene). The composition of the complexes CoCl₂ · L₂ and [Rh(cod)(L₂)]X (L₂ = 1, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane; X = Cl, TfO) was studied using IR and ¹H NMR spectroscopy. In the Rh^I cyclooctadienediamine complexes, the diene molecule forms a stronger bond with the metal atom than that in the cyclooctadienediphosphine analogs. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2270–2274, October, 2005.