Triterpenoid Saponins from Vaccaria segetalis

Four novel triterpenoid saponins, Vaccariside B‐E (1–4), were isolated from the seeds of Vaccaria segetalis and their structures were elucidated as 3‐O‐β‐D‐galactopyranosyl‐(1–2)‐β‐D‐glucuronopyranosyl quillaic add 28‐O‐β‐D‐xylopyranosyl‐(1–3)‐α‐L rhamno‐pyranosyl‐(1–2)‐[α‐L‐arabinofura‐nosyl‐(1–3)]‐4‐O‐acetyl‐β‐D)‐fucopyranoside (1), 3‐O‐β‐D‐galactopyranosyl ‐ (1–2) ?3‐O‐acetyl‐β‐D ‐ glucuronopyranosyl quillaic acid 28‐O‐β‐D‐xylopyranosyl‐(1–3)‐α‐L‐rhamnopyra‐nosyl‐(1–2)‐[α‐L‐arabinofuranosyl‐(1–3)]‐4‐O‐acetyl‐β‐D‐fucopyranoside (2), 3‐O‐β‐D‐galactopyranosyl‐(1–2)‐β‐D‐glucuronopyranosyl quillaic add 28‐O‐α‐L‐arabinopyranosyl‐(1–3)‐α‐L‐rhamnopyranosyl‐(1–2)‐[α‐L‐arabinofuranosyl‐(1–3)]‐4‐O‐acetyl‐β‐D‐fucopyranoside (3), 3‐O‐β‐D‐galacto‐pyranosyl‐(1–2)‐[β‐D‐xytopyranosyl‐(1–3)]‐β‐D‐glucurono‐pyranosyl quillaic add 28‐O‐β‐D‐xylopyranosyl‐(1–3)‐α‐L‐rhamnopyranosyl‐(1–2)‐[α‐L‐arabinofuranosyl‐(1–3)]‐4‐O‐acetyl‐β‐D‐fucopyranoside (4), respectively.     

Influence of substituted groups on the binding ability of benzoyl-modified β-cyclodextrins

A series of substituted benzoyl modified β-cyclodextrins, including mono-6-O-(p-methylbenzoyl)-β-CD (1), mono-6-O-(m-methylbenzoyl)-β-CD (2), mono-6-O-(o-methylbenzoyl)-β-CD (3), mono-6-O-(p-methoxylbenzoyl)-β-CD (4), mono-6-O-(m-methoxylbenzoyl)-β-CD (5), mono-6-O-(o-methoxylbenzoyl)-β-CD (6), mono-6-O-(m, p-dimethoxylbenzoyl)]-β-CD (7), mono-6-O-(o,m-dimethoxylbenzoyl)-β-CD (8), and mono-(6-O-benzoyl)-β-CD (9) were synthesized and their inclusion properties were studied by using fluorescence spectroscopy. The binding constants (K_a) of the modified β-CD derivatives with 2-p-toluidinylnaphthalene-6-sulfonate (TNS) were determined on the basis of the fluorescence spectroscopy. The effect of types and location of substituted groups of the benzene ring of the modified β-cyclodextrins on the binding property was discussed. Results indicated that the substituents had significant influences on the binding abilities of modified β-cyclodextrins.     

Syntheses of the Enantiomers of γ-Cyclogeranic Acid, γ-Cyclocitral,and γ-Damascone: Enantioselective protonation of enolates

(R)-and (S)-γ-cyclogeranic acid ((R)-and (S)- 9 , resp.) were obtained by resolution of the racemate, and their absolute configurations determined by chemical correlation. The γ-acids (R)-and (S)- 9 were converted into (R)-and (S)-methyl γ-cyclogeranate ((R)-and (S)- 6 , resp.), and (R)-and (S)-γ-damascone ((R)-and (S)- 5 , resp.). A more direct entry to (R)-and (S)- 9 consisted in the enantioselective protonation of a thiol ester enolate with (?)- or (γ)-N-isopropylephedrine((?)- or (γ)- 20 ) and subsequent hydrolysis of the (R)-and (S)-S-phenyl γ-thiocyclogeranate ((R)- and (S)- 24 , resp.; 97% ee). The esters (R)- and (S)- 24 were also used as precursors of (R)- and (S)-γ-damascone ((R)- and (S)- 5 , resp.). Alternatively, (S)- 5 (75% ee) was obtained by enantioselective protonation of ketone enolate 29 with (?)-N-isopropylephedrine ((?)- 20 ). Organoleptic evaluation demonstrated that the (S)-enantiomers of methyl γ-cyclogeranate and γ-damascone are markedly superior to their (R)-enantiomers.     

New Furostanol Glycosides from the Roots of Digitalis ciliata Trautv.

Three new furostanol glycosides, named ciliatasides A, B, and C ( 1 – 3 , resp.), have been isolated from the roots of Digitalis ciliata, along with two known furostanol glycosides. The structures of the new compounds were identified as (2α,3β,5α,14β,25R)‐26‐(β‐D ‐glucopyranosyloxy)‐2‐hydroxyfurost‐20(22)‐en‐3‐yl β‐D ‐glucopyranosyl‐(1→2)‐[β‐D ‐glucopyranosyl‐(1→3)]‐β‐D ‐galactopyranoside ( 1 ), (2α,3β,5α,14β,22R)‐26‐(β‐D ‐glucopyranosyloxy)‐2‐hydroxy‐22‐methoxyfurost‐25(27)‐en‐3‐yl β‐D ‐galactopyranosyl‐(1→2)‐[β‐D ‐xylopyranosyl‐(1→3)]‐β‐D ‐glucopyranosyl‐(1→4)‐β‐D ‐galactopyranoside ( 2 ), and (2α,3β,5α,14β,22R,25R)‐26‐(β‐D ‐glucopyranosyloxy)‐2,22‐dihydroxyfurostan‐3‐yl β‐D ‐glucopyranosyl‐(1→2)‐[β‐D ‐glucopyranosyl‐(1→3)]‐β‐D ‐galactopyranoside ( 3 ).     

Nine New Sesquiterpenes from Dendrobium nobile

Nine new sesquiterpenes, i.e., dendronobilins A–I ( 1 – 9 ), with copacamphane‐type ( 1 ), picrotoxane‐type ( 2 – 6 ), muurolene‐type ( 7 ), alloaromadendrane‐type ( 8 ), and cyclocopacamphane‐type ( 9 ) skeletons, were isolated from the 60% EtOH extract of the stems of Dendrobium nobile. Their structures were established as (1R,2R,4S,5S,6S,8S,9R)‐2,8‐dihydroxycopacamphan‐15‐one ( 1 ), (2β,3β,4β,5β)‐2,4,11‐trihydroxypicrotoxano‐3(15)‐lactone ( 2 ), (2β,3β,5β,9α,11β)‐2,11‐epoxy‐9,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 3 ), (2β,3β,5β,12R*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 4 ), (2β,3β,5β,12S*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 5 ), (2β,3β,5β,9α)‐9,10‐cyclo‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 6 ), (9β,10α)‐muurol‐4‐ene‐9,10,11‐triol ( 7 ), (10α)‐alloaromadendrane‐10,12,14‐triol ( 8 ), and (5β)‐cyclocopacamphane‐5,12,15‐triol ( 9 ) on the basis of spectroscopic analysis. The absolute configuration of compound 1 was tentatively assigned as (1R,2R,4S,5S,6S,8S,9R) according to its CD spectrum and the octant rule. Compounds 1 and 4 – 9 were inactive in our preliminary in vitro immunomodulatory bioassay.     

Synthesis of bottlebrush block copolymers from bottlebrush polystyrene and bottlebrush random copolymer of ω-end-norbornyl polymethacrylates and their self-assembly

Six different bottlebrush block copolymers (BBCPs) (A-b-(B-co-C)) from bottlebrush polystyrene (A) and bottlebrush random copolymers (B-co-C) of polymethacrylates were synthesized through living anionic polymerization and ring-opening metathesis polymerization. To induce the phase separation of bottlebrush polystyrene (PNB-g-PS) (A) and bottlebrush poly(benzyl methacrylate) (PNB-g-PBzMA) (C)-based BBCP with an extremely low Flory–Huggins interaction parameter (χ), three kinds of bottlebrush polymethacrylates (B): poly(norbornene-g-methyl methacrylate) (PNB-g-PMMA), poly(norbornene-g-tert-butyl methacrylate) (PNB-g-PtBMA), and poly(norbornene-g-methacrylic acid) (PNB-g-PMAA), respectively, were randomly combined with C. An order–disorder phase transition of the BBCPs (A-b-(B-co-C)) was observed with a change in mole ratios of PMMA, PtBMA, or PMAA to PBzMA of 25, 50, and 75% in random copolymer blocks using field-emission scanning microscopy. While the BBCP with 25% of PMAA in the random copolymer block showed an ordered lamellar nanostructure, a disordered morphology was revealed at 75% PMAA. SEM showed that the incorporation of PtBMA and PBzMA showed better-ordered lamellar morphologies than was the case with PMMA and PBzMA at the same mole ratios.     

Thermische (E), (Z)-Isomerisierungen bei substituierten Propenylbenzolen

Thermal (E), (Z)-Isomerizations of Substituted Propenylbenzenes The thermal isomerizations of (E)- and (Z)-3,5-dimethyl-2-(1′-propenyl)phenol ((E)- and (Z)- 3 ), (E)- and (Z)-N-methyl-2-(1′-propenyl)anilin ((E)- and (Z)- 4 ), (E)- and (Z)-3,5-dimethyl-2-(1′-propenyl)anilin ((E)- and (Z)- 5 , (E)- and (Z)-2-(1′-propenyl)mesitylene ((E)- and (Z- 6 ), (E)- and (Z)-2-(1′-propenyl)mesitylene ((E)- and (Z)- 7 ), (E)- and (Z)-2-(1′-propenyl)toluene ((E)- and (Z)- 8 ), (E)- and (Z)-4-(1′-propenyl)toulene ((E)- and (Z)- 9 ) as well as of (E)- and (Z)-2-(2′-butenyl)-mesitylene ((E)- and (Z)- 10 ) in decane solution were studied (Scheme 2). Whereas the isomerization of the 2-propenylphenols (E)- and (Z)- 3 occurs already between 130 and 150° (cf. Table 1), the isomerization of the 2-propenylanilins 4 and 5 takes place only at temperatures between 220 and 250° (cf. Tables 2 and 3). The activation values and the experiments using N-deuterated 4 (cf. Scheme 4) show that 2-propenylphenols and -anilins isomerize via sigmatropic [1,5]-hydrogen-shifts. For the isomerization of the methyl-substituted propenylbenzenes temperatures > 360° are required (cf. Tables 4 and 5). The activation values of the isomerization of (E)- and (Z)- 6 and (E)- and (Z)- 9 are in accord with those of other (E), (Z)-isomerizations which occur via vibrationally excited singlet biradicals (cf. Table 7). Nevertheless, thermal isomerization of 2′-d-(Z)- 8 (cf. Scheme 6) demonstrates that during the reaction deuterium is partially transfered into the ortho-methyl group, i.e. 1,5-hydrogen-shifts must have participated in isomerization of (E)- and (Z)- 8 (cf. Scheme 8). Under the equilibrium conditions 2,4,6-trimethylindan ( 17 ) is formed slowly at 368° from (E)- and (Z)- 6 , very probably via a radical 1,4-hydrogen-shift (cf. Scheme 9). In a similar way 2-ethyl-4,6-dimethylindan ( 19 ; cf. Table 6) arises from (E)- and (Z)- 7 . Thermolysis of (E)- and (Z)- 10 in decane solution at 367° results in almost no (E),(Z)-isomerization. At prolonged heating 19 and 2,5,7-trimethyl-1,2,3,4-tetrahydronaphthalene ( 20 ) are formed; these two products arise very likely from an intermolecular radical process (cf. Scheme 10).     

Synthesis,Isolation, and Full Spectroscopic Characterization of Eleven (Z)-Isomers of (3R,3′R)-Zeaxanthin

Developmental efforts to improve the yield of the chemical synthesis of (3R,3′R)-zeaxanthin resulted in the isolation, partly by chromatography from reaction mixtures, and full spectroscopic characterization by ¹H-NMR, UV/VIS, and CD spectrosocpy of eleven (Z/E)-isomers of zeaxanthin: (7Z)-, (9Z), (13Z)-, (15Z)-, (7Z,7′Z)-, (9Z,9′Z)- (7Z,9Z,7Z)-, (7Z,11Z,7′Z)-, (9Z,13Z,9′Z)-, (7Z,9Z,7′Z,9′Z)-, and (7Z,9Z,11Z,7′Z,9′Z)-zeaxanthin. Five of these isomers were obtained by specific synthesis, namely the (7Z)-, (7Z,7′Z)-, (9Z,9′Z)-, (7Z,9Z,7′Z)-, and (7Z,9Z,7′Z-9Z)-isomers.     

Sesquiterpenoids and Lactone Derivatives from Ligularia dentata

Seven new compounds were isolated from the roots of Ligularia dentata, including five bisabolane‐type sesquiterpenoids (bisabolane=1‐(1,5‐dimethylhexyl)‐4‐methylcyclohexane), namely (8β,10α)‐8‐(angeloyloxy)‐5,10‐epoxybisabola‐1,3,5,7(14)‐tetraene‐2,4,11‐triol ( 1 ), (8β,10α)‐8‐(angeloyloxy)‐5,10‐epoxythiazolo[5,4‐a]bisabola‐1,3,5,7(14)‐tetraene‐4,11‐diol ( 2 ), (1α,2α,3β,5α,6β)‐1,5,8‐tris(angeloyloxy)‐10,11‐epoxy‐2,3‐dihydroxybisabol‐7(14)‐en‐4‐one ( 3 ), (1α,2α,3β,5α,6β)‐2,5,8‐tris(angeloyloxy)‐10,11‐epoxy‐1,3‐dihydroxybisabol‐7(14)‐en‐4‐one ( 4 ), and (1α,2β,3β,5α,6β)‐1,8‐bis(angeloyloxy)‐2,3‐epoxy‐5,10‐dihydroxy‐11‐methoxybisabol‐7(14)‐en‐4‐one ( 5 ) (angeloyloxy=[(2Z)‐2‐methyl‐1‐oxobut‐2‐enyl]oxy), and two lactone derivatives, (2α,3β,5α)‐2‐(acetyloxy)‐9‐methoxy‐5‐(methoxycarbonyl)‐2,3‐dimethylheptano‐5‐lactone ( 6 ), and (2β,4β)‐2‐ethyl‐5‐hydroxy‐5‐(methoxycarbonyl)‐4,5‐dimethylpentano‐4‐lactone ( 7 ) (α/β denote relative configurations), together with (2E,4R,5S)‐2‐ethylidene‐5‐(methoxycarbonyl)‐4‐methylhexano‐5‐lactone ( 8 ), a known synthetic compound. Compound 2 is the first sesquiterpenoid derivative containing the uncommon benzothiazole moiety. The structures of 1 – 8 were established by spectroscopic methods, especially 2D‐NMR and MS analyses.     

Three Escin‐Like Triterpene Saponins: Assamicins VI,VII, and VIII from the Seeds of Aesculus assamica Griff

Three new escin‐like triterpene saponins, assamicins VI ( 1 ), VII ( 2 ), and VIII ( 3 ), were isolated from the seeds of A. assamica, together with a known saponin, isoescin Ib ( 4 ). Their structures were established as 28‐O‐acetyl‐21‐O‐(3,4‐di‐O‐angeloyl‐6‐deoxy‐β‐glucopyranosyl)‐3‐O‐{O‐β‐glucopyranosyl‐(1→2)‐O‐[β‐glucopyranosyl‐(1→4)]‐β‐glucopyranuronosyl}protoaescigenin ( 1 ), 21‐O‐angeloyl‐3‐O‐{O‐α‐rhamnopyranosyl‐(1→2)‐O‐[β‐glucopyranosyl‐(1→3)]‐β‐glucopyranuronosyl}protoaescigenin ( 2 ), and 21‐O‐angeloyl‐3‐O‐{O‐[β‐glucopyranosyl‐(1→3)]‐β‐glucopyranuronosyl}protoaescigenin ( 3 ) on the basis of spectroscopic analysis (protoaescigenin=(3β,4β,16α,21β,22α)‐olean‐12‐ene‐3,16,21,22,23,28‐hexol; angelic acid=(2Z)‐2‐methylbut‐2‐enoic acid).     

Novel block–comb/graft copolymers with the macromonomer strategy and anionic polymerization

The following block–comb/graft copolymers of styrene (S), isoprene (I), and butadiene (B)—PS‐b‐(PB‐g‐PB), PS‐b‐(PB‐g‐PB)‐b‐PS, (PB‐g‐PB)‐b‐P2VP, (PS‐g‐PB)‐b‐(PI‐g‐PS), (PS‐g‐PB)‐b‐(PI‐g‐PS)‐b‐(PB‐g‐PI), (PS‐g‐PB)‐b‐(PI‐g‐PS)‐b‐(PB‐g‐PI)‐b‐(PI‐g‐PS)‐b‐(PS‐g‐PB), and (PS)₂(PB‐g‐PB) [where PS is polystyrene, PB is polybutadiene, P2VP is poly(2‐vinylpyridine) (2VP), and PI is polyisoprene]—were synthesized with the macromonomer strategy and anionic polymerization high‐vacuum techniques. The synthetic approach involves the synthesis and block copolymerization of styrenic macromonomers in situ without isolation. The prepared samples were characterized by size exclusion chromatography with a differential refractometer detector, size exclusion chromatography with a two‐angle laser light scattering detector, and NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4040–4049, 2005     

Stereochemical Models for Discussing Additions to α,β‐Unsaturated Aldehydes Organocatalyzed by Diarylprolinol or Imidazolidinone Derivatives – Is There an ‘(E)/(Z)‐Dilemma’?

The structures of iminium salts formed from diarylprolinol or imidazolidinone derivatives and α,β‐unsaturated aldehydes have been studied by X‐ray powder diffraction (Fig. 1), single‐crystal X‐ray analyses (Table 1), NMR spectroscopy (Tables 2 and 3, Figs. 2–7), and DFT calculations (Helv. Chim. Acta 2009 , 92, 1, 1225, 2010 , 93, 1; Angew. Chem., Int. Ed. 2009 , 48, 3065). Almost all iminium salts of this type exist in solution as diastereoisomeric mixtures with (E)‐ and (Z)‐configured ⁺NC bond geometries. In this study, (E)/(Z) ratios ranging from 88 : 12 up to 98 : 2 (Tables 2 and 3) and (E)/(Z) interconversions (Figs. 2–7) were observed. Furthermore, the relative rates, at which the (E)‐ and (Z)‐isomers are formed from ammonium salts and α,β‐unsaturated aldehydes, were found to differ from the (E)/(Z) equilibrium ratio in at least two cases (Figs. 4 and 5, a, and Fig. 6, a); more (Z)‐isomer is formed kinetically than corresponding to its equilibrium fraction. Given that the enantiomeric product ratios observed in reactions mediated by organocatalysts of this type are often ≥99 : 1, the (E)‐iminium‐ion intermediates are proposed to react with nucleophiles faster than the (Z)‐isomers (Scheme 5 and Fig. 8). Possible reasons for the higher reactivity of (E)‐iminium ions (Figs. 8 and 9) and for the kinetic preference of (Z)‐iminium‐ion formation are discussed (Scheme 4). The results of related density functional theory (DFT) calculations are also reported (Figs. 10–13 and Table 4).     

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.     

Asymmetric Phase-Transfer Catalysis by Quaternary Ammonium Ions Derived from Cinchona-Alkaloid Analogs Containing 1,1′-Binaphthalene Moieties

The synthesis and catalytic properties of a new type of enantioselective phase-transfer catalysts, incorporating both the quinuclidinemethanol fragment of Cinchona alkaloids and a 1,1′-binaphthalene moiety, are described. Catalyst (+)-(aS,3R,4S,8R,9S)- 4 with the quinuclidine fragment attached to C(7′) in the major groove of the 1,1′-binaphthalene residue was predicted by computer modeling to be an efficient enantioselective catalyst for the unsymmetric alkylation of 6,7-dichloro-5-methoxy-2-phenylindanone ( 1 ; Scheme 1, Fig. 1). Its synthesis involved the selective oxidative cross-coupling of two differently substituted naphthalen-2-ols to afford the asymmetrically substituted 1,1′-binaphthalene derivative (±)- 17 in high yield (Scheme 3). Chromatographic optical resolution via formation of diastereoisomeric camphorsulfonyl esters and functional-group manipulation gave access to the 7-bromo-1,1′-binaphthalene derivative (−)-(aS)- 11 (Scheme 4). Nucleophilic addition of lithiated (−)-(aS)- 11 to the quinuclidine Weinreb amide (+)-(3R,4S,8R)- 8 afforded the two ketones (aS,3R,4S,8R)- 27 and (aS,3R,4S,8S)- 28 as an inseparable mixture of diastereoisomers (Scheme 6). Stereoselective reduction of this mixture with DIBAL-H (diisobutylaluminum hydride; preferred formation of the C(8)−C(9) erythro-pair of diastereoisomers with 18% de) or with NaBH₄ (preferred formation of the threo-pair of diastereoisomers with 50% de) afforded the four separable diastereoisomers (+)-(aS,3R,4S,8S,9S)- 29 , (+)-(aS,3R,4S,8R,9R)- 30 , (−)-(aS,3R,4S,8S,9R)- 31 , and (+)-(aS,3R,4S,8R,9S)- 32 (Scheme 6). A detailed conformational analysis, combining ¹H-NMR spectroscopy and molecular-mechanics computations, revealed that the four diastereoisomers displayed distinctly different conformational preferences (Figs. 2 and 3). These novel Cinchona-alkaloid analogs were quaternized to give (+)-(aS,3R,4S,8R,9S)- 4 , (+)-(aS,3R,4S,8S,9S)- 5 , (+)-(aS,3R,4S,8R,9R)- 6 , and (−)-(aS,3R,4S,8S,9R)- 7 (Scheme 7) which were tested as phase-transfer agents in the asymmetric allylation of phenylindanone 1 . Without any optimization work, (+)-(aS,3R,4S,8R,9S)- 4 was found to catalyze the allylation of 1 yielding the predicted enantiomer (+)-(S)- 3b in 32% ee. The three diastereoisomeric catalysts (+)- 5 , (+)- 6 , and (−)- 7 gave access to lower enantioselectivities (6 to 22% ee's), which could be rationalized by computer modeling (Fig. 4).     

Two New Phenylethanoid Glycosides from Callicarpa longissima

Two new phenylethanoid glycosides, longissimosides A and B ( 1 and 2 , resp.), together with eight structurally related known compounds, were isolated from the EtOH extract of leaves and stems of Callicarpa longissima (Hemsl .) Merr . The structures of 1 and 2 were elucidated as 2‐(3,4‐dihydroxyphenyl)ethyl O‐(α‐L ‐rhamnopyranosyl)‐(1→3)‐O‐(2‐O‐syringoyl‐β‐D ‐xylopyranosyl)‐(1→6)‐ 4‐O‐[(E)‐caffeoyl]‐β‐D ‐glucopyranoside ( 1 ) and 2‐(3‐hydroxy‐4‐methoxyphenyl)ethyl O‐(α‐L ‐rhamnopyranosyl)‐(1→3)‐O‐(β‐D ‐apiofuranosyl)‐(1→6)‐4‐O‐[(E)‐isoferuloyl]‐β‐D ‐glucopyranoside ( 2 ) on the basis of spectroscopic data and acid hydrolysis.     

An Investigation into Domino‐Heck Reactions of N‐Acylamino‐Substituted Tricyclic Imides: Synthesis of New Prospective Pharmaceuticals

Heck and domino‐Heck reactions of unsaturated N‐acylamino‐substituted tricyclic imides with aryl(heteroaryl) iodides and phenyl‐ or (trimethylsilyl)acetylene were either carried out in the presence of formate or phenyl‐ and (trimethylsilyl)acetylene, respectively. The C? C coupling reactions appeared to be completely diastereoselective, giving the corresponding N‐acylamino‐5‐exo‐aryl (heteroaryl)‐ ( 5a – c, 6a , b ), N‐(benzoylamino)‐5‐exo‐phenyl‐6‐exo‐[(trimethylsilyl)ethynyl]‐ ( 5d ), or 5‐exo‐(4‐chlorophenyl)‐N‐(2,2‐dimethylpropanoylamino)‐6‐exo‐(phenylethynyl)bicyclo[2.2.1]heptane‐2‐endo,3‐endo‐dicarboximide ( 6c ) (Schemes 3 and 4).     

Two New C-21 Steroidal Glycosides from the Stems of Stephanotis mucronata

Two new C-21 steroidal glycosides, mucronatosides M（1） and N（2）, were isolated from the stems of Stephanotis mucronata, together with one known compound stephanoside M（3）. On the basis of chemical evidence and extensive spectroscopic methods, including one-dimensional and two-dimensional NMR, the structures of the two new compounds were identified as 12-O-tigloyl-20-O-N-methylanthraniloyl sarcoslin 3-O-β-D-glucopyranosyl-（1→4）-6- deoxy-3-O-methyl-β-D-allopyranosyl-（→4）-β-D-cymaropyranosyl-（1→4）-β-D-cymaropyranoside （1）, and 12-O- cinnamoyl-20-O-nicotinoyl（ 2OS）-pregn-6-ene-3 β,5α,8βm12 β,14β,17β,20-heptanol 3-O-β-D-glucopyranosyl-（1→4）-6- deoxy-3-O-methyl-β-D-allopyranosyl-（1→4）-β-D-cymaropyranosyl-（1→4）-β-D-cymaropyranoside （2）.     

Study on Self-assembly of Poly(ethylene glycol)- block-poly(γ-benzyl L -glutamate)-graft-poly(ethylene glycol) Copolymer and Poly(γ-benzyl L -glutamate)- block-poly(ethylene glycol) Copolymer in Ethanol

Poly(ethylene glycol)-block-poly(γ-benzyl L-glutamate)-graft-poly(ethylene glycol) (PEG-b-PBLG-g-PEG) copolymer was synthesized by the ester exchange reaction of poly(γ-benzyl L-glutamate)-block-poly(ethylene glycol) (PBLG-block-PEG) copolymer with PEG chain, and PBLG-block-PEG copolymer was prepared by a standard N-carboxyl-γ-benzyl-L-glutamate anhydride (NCA) method. Nuclear magnetic resonance (NMR) spectroscopy was used to confirm the components of PBLG-block-PEG and PEG-b-PBLG-g-PEG. The self-association behaviors of PBLG-block-PEG and PEG-b-PBLG-g-PEG in ethanol were investigated by transmission electron microscopy (TEM), dynamic laser scattering (DLS), and viscometry. The experimental results revealed that the different molecular structures could exert marked effects on the self-assembly behaviors of PBLG-block-PEG and PEG-b-PBLG-g-PEG in ethanol. PBLG-block-PEG and PEG-b-PBLG-g-PEG could self-assemble to form polymeric micelles with a core-shell structure in the shapes of plump spherical and regular rice-like, respectively. Effects of the introduction of PBLG homopolymer on the average particle diameter of the micelles of PBLG-block-PEG and PEG-b-PBLG-g-PEG and influence of testing temperature on the critical micelle concentration of different copolymers were studied.     

Über Kaliumtetracyanoplatinat(II), Kaliumtetracyanopalladat(II) und deren Monohydrate

We have determined the crystal structures of the potassium tetracyanoplatinates(II) and ‐palladates(II), and of their monohydrates, by X‐ray powder diffraction techniques and single crystal structure analysis. K₂[Pt(CN)₄]: orthorhombic; Pccn; a = 1370.11(2); b = 907.09(1); c = 703.91(2) pm; Z = 4; R_F² = 0.0903 (N(hkl) = 415). K₂[Pt(CN)₄] · H₂O: orthorhombic; Pnna; a = 715.79(4); b = 977.91(6); c = 1322.46(8) pm; Z = 4; R(F)_N′ = 0.027 (N′(hkl) = 1066). K₂[Pd(CN)₄]: monoclinic; P2₁/c; a = 433.03(2); b = 782.90(3); c = 1328.17(6) pm; ß = 93.069(3)°; Z = 2; R_p = 0.0583 (N(hkl) = 352). K₂[Pd(CN)₄] · H₂O: orthorhombic; Pnna; a = 721.48(6); b = 976.77(8); c = 1326.4(1) pm; Z = 4; R(F)_N′ = 0.048 (N′(hkl) = 1137). In all examined representatives the anions are stacked one upon the other, even though they are tilted in part. The results are completed by spectroscopic and thermo analytical investigations.     

New Approach to Determine the Phase Transition Temperature,Cloud Point,of Thermoresponsive Polymers

In this study, a novel method to determine the cloud point temperature variation in aqueous solutions of thermoresponsive homo- and copolymers was developed. Poly(N-vinylcaprolactam) (PVCL) and triblock copolymers of poly(t-butyl acrylate-co-acrylic acid)-b-poly(N-vinylcaprolactam)-b-(t-butyl acrylate-co-acrylic acid) (P[(tBA-co-AA)-b-PVCL-b-P(tBA-co-AA)] were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and used as models. The incorporation of AA units (hydrophilic segments) into the polymeric chain of PVCL influenced the phase transition, increasing the cloud point temperature of the final copolymer. The cloud point temperatures of the PVCL and the triblock copolymer P(tBA-co-AA)-b-PVCL-b-P(tBA-co-AA) were determined by measuring the transmittance of aqueous solutions of the polymers in a Turbiscan Lab instrument in the range of 29 to 40 C. This is the first study in which Turbiscan Lab is used to determine the cloud point temperature.