Synthesis of Substituted α‐(Hydroxymethyl)‐β‐iodoacrylates via MgI2‐Promoted Stereoselective Aldol Coupling

The efficient and highly stereoselective syntheses of a variety of (Z)‐configured, substituted α‐(hydroxymethyl) ‐ β‐iodo‐acrylates from prop‐2‐ynoate and various aldehydes was achieved. The synthetic protocol involves a simple one‐pot coupling reaction under mild conditions, promoted by MgI₂, which serves both as a Lewis acid and iodine source for a Baylis? Hillman‐type reaction. All adducts were generated in good‐to‐excellent yields, the (Z)‐isomers being formed in high selectivity (>98%). The conversion of methyl prop‐2‐ynoate into an active ‘β‐iodo allenolate’ intermediate, which then nucleophilically attacks an aldehyde, is proposed as a plausible reaction mechanism.     

Iron-mediated and -catalyzed metalative cyclization of electron-withdrawing-group-substituted alkynes and alkenes with Grignard reagents

Treatment of ethyl (E)‐5,5‐bis[(benzyloxy)methyl]‐8‐(N,N‐diethylcarbamoyl)‐2‐octen‐7‐ynoate with an iron reagent generated from FeCl₂ and tBuMgCl in a ratio of 1:4 (abbreviated as FeCl₂/4 tBuMgCl) afforded ethyl [4,4‐bis[(benzyloxy)methyl]‐2‐[(E)‐(N,N‐diethylcarbamoyl)methylene]cyclopent‐1‐yl]acetate in good yield. Deuteriolysis of an identical reaction mixture afforded the bis‐deuterated product ethyl [4,4‐bis[(benzyloxy)methyl]‐2‐[(E)‐(N,N‐diethylcarbamoyl)deuteriomethylene]cyclopent‐1‐yl]deuterioacetate, thus confirming the existence of the corresponding dimetalated intermediate. The latter intermediate can react with halogens or aldehydes to facilitate further synthetic transformations. The amount of FeCl₂ was reduced to catalytic levels (10 mol % relative to enyne), and catalytic cyclizations of this sort proceeded with yields comparable to those of the aforementioned stoichiometric reactions. The cyclization of diethyl (E,E)‐2,7‐nonadienedioate with a stoichiometric amount of FeCl₂/4 tBuMgCl, followed by the addition of sBuOH as a proton source, afforded a mixture of 2‐(ethoxycarbonyl)‐3‐bicyclo[3.3.0]octanone and its enol form in good yield. The use of aldehyde or ketone in place of sBuOH afforded 2‐(ethoxycarbonyl)‐3‐bicyclo[3.3.0]octanone, which has an additional hydroxyalkyl side chain. Additionally, the metalation of a carbon–carbon unsaturated bond in N,N‐diethyl‐5,5‐bis[(benzyloxy)methyl]‐7,8‐epoxy‐2‐octynamide or (E)‐3,3‐dimethyl‐6‐(N,N‐diethylcarbamoyl)‐5‐hexenyl p‐toluenesulfonate with FeCl₂/4 tBuMgCl or FeCl₂/4 PhMgBr was followed by an intramolecular alkylation with an epoxide or alkyl p‐toluenesulfonate to afford 5,5‐bis[(benzyloxy)methyl]‐3‐[(E)‐(N,N‐diethylcarbamoyl)methylene]‐1‐cyclohexanol or N,N‐diethyl(3,3‐dimethylcyclopentyl)acetamide after hydrolysis. In both cases, the remaining metalated portion α to the amide group was confirmed by deuteriolysis and could be utilized for an alkylation with methyl iodide.     

Regioselective 1,3‐Dipolar Cycloadditions of (1Z)‐1‐(Arylmethylidene)‐5,5‐dimethyl‐3‐oxopyrazolidin‐1‐ium‐2‐ide Azomethine Imines to Acetylenic Dipolarophiles

The 5,5‐dimethylpyrazolidin‐3‐one ( 4 ), prepared from ethyl 3‐methylbut‐2‐enoate ( 3 ) and hydrazine hydrate, was treated with various substituted benzaldehydes 5a – i to give the corresponding (1Z)‐1‐(arylmethylidene)‐5,5‐dimethyl‐3‐oxopyrazolidin‐1‐ium‐2‐ide azomethine imines 6a – i . The 1,3‐dipolar cycloaddition reactions of azomethine imines 6a – h with dimethyl acetylenedicarboxylate (=dimethyl but‐2‐ynedioate; 7 ) afforded the corresponding dimethyl pyrazolo[1,2‐a]pyrazoledicarboxylates 8a – h , while by cycloaddition of 6 with methyl propiolate (=methyl prop‐2‐ynoate; 9 ), regioisomeric methyl pyrazolo[1,2‐a]pyrazolemonocarboxylates 10 and 11 were obtained. The regioselectivity of cycloadditions of azomethine imines 6a – i with methyl propiolate ( 9 ) was influenced by the substituents on the aryl residue. Thus, azomethine imines 6a – e derived from benzaldehydes 5a – e with a single substituent or without a substituent at the ortho‐positions in the aryl residue, led to mixtures of regioisomers 10a – e and 11a – e . Azomethine imines 6f – i derived from 2,6‐disubstituted benzaldehydes 5f – i gave single regioisomers 10f – i .     

Novel chalcones derived from 2‐chloro‐3‐formyl‐6‐methylquinoline

Molecules of (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐iodo‐2‐thienyl)prop‐2‐en‐1‐one, C₁₇H₁₁ClINOS, (I), and (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐methyl‐2‐furyl)prop‐2‐en‐1‐one, C₁₈H₁₄ClNO₂, (II), adopt conformations slightly twisted from coplanarity. Both structures are devoid of classical hydrogen bonds. However, nonclassical C—H...O/N interactions [with C...O = 3.146 (5) Å and C...N = 3.487 (3) Å] link the molecules into chains extended along the b axis in (I) and form dimers with an R₂²(8) motif in (II). The structural analysis of these compounds provides an insight into the correlation between molecular structures and intermolecular interactions in compounds for drug development.     

Oxidative Fragmentations of the 5α‐ and 5β‐Hydroxy‐B‐norcholestan‐ 3β‐yl Acetates

Oxidations of 5α‐hydroxy‐B‐norcholestan‐3β‐yl acetate ( 8 ) with Pb(OAc)₄ under thermal or photolytic conditions or in the presence of iodine afforded only complex mixtures of compounds. However, the HgO/I₂ version of the hypoiodite reaction gave as the primary products the stereoisomeric (Z)‐ and (E)‐1(10)‐unsaturated 5,10‐seco B‐nor‐derivatives 10 and 11 , and the stereoisomeric (5R,10R)‐ and (5S,10S)‐acetals 14 and 15 (Scheme 4). Further reaction of these compounds under conditions of their formation afforded, in addition, the A‐nor 1,5‐cyclization products 13 and 16 (from 10 ) and 12 (from 11 ) (see also Scheme 6) and the 6‐iodo‐5,6‐secolactones 17 and 19 (from 14 and 15 , resp.) and 4‐iodo‐4,5‐secolactone 18 (from 15 ) (see also Scheme 7). Oxidations of 5β‐hydroxy‐B‐norcholestan‐3β‐yl acetate ( 9 ) with both hypoiodite‐forming reagents (Pb(OAc)₄/I₂ and HgO/I₂) proceeded similarly to the HgO/I₂ reaction of the corresponding 5α‐hydroxy analogue 8 . Photolytic Pb(OAc)₄ oxidation of 9 afforded, in addition to the (Z)‐ and (E)‐5,10‐seco 1(10)‐unsaturated ketones 10 and 11 , their isomeric 5,10‐seco 10(19)‐unsaturated ketone 22 , the acetal 5‐acetate 21 , and 5β,19‐epoxy derivative 23 (Scheme 9). Exceptionally, in the thermal Pb(OAc)₄ oxidation of 9 , the 5,10‐seco ketones 10, 11 , and 22 were not formed, the only reaction being the stereoselective formation of the 5,10‐ethers with the β‐oriented epoxy bridge, i.e. the (10R)‐enol ether 20 and (5S,10R)‐acetal 5‐acetate 21 (Scheme 8). Possible mechanistic interpretations of the above transformations are discussed.     

Two Antioxidant Alkaloids from Portulaca oleracea L.

Two alkaloids, oleraceins F and G, were isolated from Portulaca oleracea L., and their structures were determined as methyl (2S)‐6‐[(β‐D ‐glucopyranosyl)oxy]‐2,3‐dihydro‐5‐hydroxy‐1‐[(2E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoyl]‐1H‐indole‐2‐carboxylate and methyl (2S)‐6‐[(β‐D ‐glucopyranosyl)oxy]‐2,3‐dihydro‐5‐hydroxy‐1‐[(2E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoyl]‐1H‐indole‐2‐carboxylate, based on their spectroscopic data. Oleraceins F and G exhibited scavenging activity against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical, with EC₅₀ values of 21.00 and 37.69 μM , respectively.     

One‐Pot,Asymmetric and Diastereoselective Four‐Component Synthesis of Polyfunctional (Z)‐Alkenyl Methyl Sulfones with Three Stereogenic Centers

The reaction of 1‐(trimethylsilyloxy)cyclopentene ( 9 ) with (±)‐1,3,5‐triisopropyl‐2‐(1‐(RS)‐{[(1E)‐2‐methylpenta‐1,3‐dienyl]oxy}ethyl)benzene ((±)‐ 4a ) in SO₂/CH₂Cl₂ containing (CF₃SO₂)₂NH, followed by treatment with Bu₄NF and MeI gave a 3.0 : 1 mixture of (±)‐(2RS)‐2{(1RS,2Z,4SR)‐2‐methyl‐4‐(methylsulfonyl)‐1‐[(RS)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐en‐1‐yl}cyclopentanone ((±)‐ 10 ) and (±)‐(2RS)‐2‐{(1RS,2Z)‐2‐methyl‐4‐[(SR)‐methylsulfonyl]‐1‐[(SR)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐en‐1‐yl}cyclopentanone ((±)‐ 11 ). Similarly, enantiomerically pure dienyl ether (−)‐(1S)‐ 4a reacted with 1‐(trimethylsilyloxy)cyclohexene ( 12 ) to give a 14.1 : 1 mixture of (−)‐(2S)‐2‐{(1S,2Z,4R)‐2‐methyl‐4‐(methylsulfonyl)‐1‐[(S)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐enyl}cyclohexanone ((−)‐ 13a ) and its diastereoisomer 14a with (1S,2R,4R) or (1R,2S,4S) configuration. Structures of (±)‐ 10 , (±)‐ 11 , and (−)‐ 13a were established by single‐crystal X‐ray crystallography. Poor diastereoselectivities were observed with the (E,E)‐2‐methylpenta‐1,3‐diene‐1‐ylethers (+)‐ 4b and (−)‐ 4c bearing ( 1 S )‐1‐phenylethyl and (1S)‐1‐(pentafluorophenyl)ethyl groups instead of the Greene's auxiliary ((1S)‐(2,4,6‐triisopropylphenyl)ethyl group). The results demonstrate that high α/β‐syn and asymmetric induction (due to the chiral auxiliary) can be obtained in the four‐component syntheses of the β‐alkoxy ketones. The method generates enantiomerically pure polyfunctional methyl sulfones bearing three chiral centers on C‐atoms and one (Z)‐alkene moiety.     

The Syntheses of Cyclic Spermine Alkaloids: Analogues of Buchnerine and Budmunchiamine C

The syntheses of two macrocyclic spermine alkaloids, analogues 1 and 2 of budmunchiamine C and buchnerine, in which N,N′‐bis(2‐aminoethyl)hexane‐1,6‐diamine (PA 262; 4 ) replaces spermine as polyamine backbone, were accomplished by two different methods. The first synthetic approach was based on a metal‐template intramolecular amidation of tetraamino esters prepared from a Michael addition of protected PA 262 10 to ethyl hexadec‐2‐ynoate ( 12 ) and ethyl prop‐2‐ynoate 17 , respectively (see Schemes 4 and 5, resp.). The consecutive Michael addition of ethane‐1,2‐diamine to unsaturated esters and aminolysis was employed in the second synthetic approach to prepare the precursors 23 and 24 (Scheme 6). The macrocyclic lactams were then constructed by macrocyclization of sulfonamido derivatives 25 and 26 in DMF with Cs₂CO₃ as catalyst.     

Isomerization of (all‐E)‐Cucurbitaxanthin A

Cucurbitaxanthin A (=(all‐E,3S,5R,6R,3′R)‐3,6‐epoxy‐5,6‐dihydro‐β,β‐carotene‐5,3′‐diol; 1 ) was submitted to thermal isomerization and to I₂‐catalysed photoisomerization. The structure of the main reaction products (9Z)‐ ( 2 ), (9′Z)‐ ( 3 ), (13Z)‐ ( 4 ), and (13′Z)‐cucurbitaxanthin A ( 5 ) was determined by their UV/VIS, CD, ¹H‐NMR, and mass spectra.     

Thioglucosides from the Seeds of Raphanus sativus L.

Three new thioglucosides, (4E)‐5‐{6‐O‐[(2E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoyl]‐β‐glucopyranosylsulfanyl}pent‐4‐enenitrile ( 1 ), (4E)‐5‐{6‐O‐[(2E)‐3‐(4‐hydroxy‐3,5‐dimethoxyphenyl)prop‐2‐enoyl]‐β‐glucopyranosylsulfanyl}pent‐4‐enenitrile ( 2 ) and its (4Z)‐isomer 3 , were isolated from the seeds of Raphanus sativus L. (radish), together with two known compounds. Their structures were determined by spectroscopic methods, including UV/VIS, 1D‐ and 2D‐NMR, FAB‐ and HR‐FAB‐MS experiments.     

A chalcone showing positional disorder,two related diarylcyclohexenones showing enantiomeric disorder and a related hydroxyterphenyl,all derived from simple carbonyl precursors

Four compounds are reported, all of which lie along a versatile reaction pathway which leads from simple carbonyl compounds to terphenyls. (2E)‐1‐(2,4‐Dichlorophenyl)‐3‐ [4‐(prop‐1‐en‐2‐yl)phenyl]prop‐2‐en‐1‐one, C₁₈H₁₄Cl₂O, (I), prepared from 4‐(prop‐1‐en‐2‐yl)benzaldehyde and 2,4‐dichloroacetophenone, exhibits disorder over two sets of atomic sites having occupancies of 0.664 (6) and 0.336 (6). The related chalcone (2E)‐3‐(4‐chlorophenyl)‐1‐(4‐fluorophenyl)prop‐2‐en‐1‐one reacts with acetone to produce (5RS)‐3‐(4‐chlorophenyl)‐5‐[4‐(propan‐2‐yl)phenyl]cyclohex‐2‐en‐1‐one, C₂₁H₂₁ClO, (II), which exhibits enantiomeric disorder with occupancies at the reference site of 0.662 (4) and 0.338 (4) for the (5R) and (5S) forms; the same chalcone reacts with methyl 3‐oxobutanoate to give methyl (1RS,6SR)‐4‐(4‐chlorophenyl)‐6‐[4‐(propan‐2‐yl)phenyl]‐2‐oxocyclohex‐3‐ene‐1‐carboxylate, C₂₃H₂₃ClO₃, (III), where the reference site contains both (1R,6S) and (1S,6R) forms with occupancies of 0.923 (3) and 0.077 (3), respectively. Oxidation, using 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone, of ethyl (1RS,6SR)‐6‐(4‐bromophenyl)‐4‐(4‐fluorophenyl)‐2‐oxocyclohex‐3‐ene‐1‐carboxylate, prepared in a similar manner to (II) and (III), produces ethyl 4′′‐bromo‐4‐fluoro‐5′‐hydroxy‐1,1′:3′,1′′‐terphenyl‐4′‐carboxylate, C₂₁H₁₆BrFO₃, (IV), which crystallizes with Z′ = 2 in the space group P. There are no significant intermolecular interactions in the structures of compounds (I) and (II), but for the major disorder component of compound (III), the molecules are linked into sheets by a combination of C—H...O and C—H...π(arene) hydrogen bonds. The two independent molecules of compound (IV) form two different centrosymmetric dimers, one built from inversion‐related pairs of C—H...O hydrogen bonds and the other from inversion‐related pairs of C—H...π(arene) hydrogen bonds. Comparisons are made with related compounds.     

The allyl complex di‐μ‐chloro‐bis­{[(1,2,3‐η)‐4‐oxo‐5,5‐di­methyl‐1‐(ethoxy­carbonyl)­hexenyl]palladium(II)}

The title compound, di‐μ‐chloro‐bis{[(2,3,4‐η)‐ethyl 6,6‐di­methyl‐5‐oxohept‐2‐enoato]­palladium(II)}, [Pd₂Cl₂(C₁₁­H₁₇­O₃)₂], is a binuclear chloro‐bridged palladium allyl complex that was obtained serendipitously From the reaction of 6,6‐di­methyl‐2‐hepten‐4‐ynoate with Na₂PdCl₄ in water‐containing alcohol. The allyl group is substituted with an ester and a tert‐butyl­carboxy group. The dimeric mol­ecules link via C—H?O contacts into a two‐dimensional network parallel to the bc plane.     

(E/Z)‐Isomerization of (all‐E)‐5,6‐Diepikarpoxanthin

(all‐E)‐5,6‐Diepikarpoxanthin (=(all‐E,3S,5S,6S,3′R)‐5,6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol; 1 ) was submitted to thermal isomerization and I₂‐catalyzed photoisomerization. The structures of the main products, i.e. (9Z)‐ ( 2 ), (9′Z)‐ ( 3 ), (13Z)‐ ( 4 ), (13′Z)‐ ( 5 ), and (15Z)‐5,6‐diepikarpoxanthin ( 6 ), were determined by their UV/VIS, CD, ¹H‐NMR, and mass spectra. In addition, (9Z,13′Z)‐ or (13Z,9′Z)‐ ( 7 ), (9Z,9′Z)‐ ( 8 ), and (9Z,13Z)‐ or (9′Z,13′Z)‐5,6‐diepikarpoxanthin ( 9 ) were tentatively identified as minor products of the I₂‐catalyzed photoisomerization.     

A highly efficient synthesis of (Z)‐1‐aryl‐2‐silyl‐1‐ stannylethenes and their conversion to (E)‐2‐ arylethenyl‐, (Z)‐2‐(2‐pyridyl)ethenyl‐ and allenyl‐silanes

A Pd(dba)₂–P(OEt)₃ combination allowed the silastannation of arylacetylenes, 1‐hexyne or propargyl alcohols with tributyl(trimethylsilyl)stannane to take place at room temperature, producing (Z)‐2‐silyl‐1‐stannyl‐1‐substituted ethenes in high yields. Novel silyl(stannyl)ethenes were fully characterized by ¹H‐, ¹³C‐, ²⁹Si‐ and ¹¹⁹Sn‐NMR as well as infrared and mass analyses. Treatment of a series of (Z)‐1‐aryl‐2‐silyl‐1‐stannylethenes and (Z)‐1‐(3‐pyridyl)‐2‐silyl‐1‐stannylethene with hydrochloric acid or hydroiodic acid in the presence of tetraethylammonium chloride (TEACl) or tetrabutylammonium iodide (TBAI) led to the exclusive formation of (E)‐trimethyl(2‐arylethenyl)silanes with high stereoselectivity. A similar reaction of (Z)‐1‐(2‐anisyl)‐2‐silyl‐1‐stannylethene also produced E‐type trimethyl[2‐(2‐anisyl)ethenyl]silane, while (Z)‐trimethyl [2‐(2‐pyridyl)ethenyl]silane was produced exclusively from (Z)‐1‐(2‐pyridyl)‐2‐silyl‐1‐stannylethene. Protodestannylation of (Z)‐1‐[hydroxy(phenyl)methyl]‐2‐silyl‐1‐stannylethene with trifluoroacetic acid took place via the β‐elimination of hydroxystannane, providing trimethyl(3‐phenylpropa‐1,2‐dienyl)silane quite easily. The destannylation products were also fully characterized. Copyright © 2007 John Wiley & Sons, Ltd.     

The E and Z isomers of 3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid

The carboxyl­ic acid group and the double bond are coplanar in (E)‐3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid, C₁₀H₇NO₃, whereas in isomeric (Z)‐3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid, also C₁₀H₇NO₃, they are almost orthogonal. In both isomers, a strong O—H⋯N hydrogen bond, with the carboxyl­ic acid group as a donor and the pyridine‐like N atom as an acceptor, and weak C—H⋯O interactions contribute to the observed supramolecular structures, which are completed by π–π stacking interactions between oxazole and benzenoid rings.     

An Improved Protocol for Regioselective Ring-Opening of Sulfonyl Aziridines with Iodine Promoted by PPh3

A new route to synthesize β-iodo amines from sulfonyl aziridines and iodine was developed in the presence of PPh3. This ring-opening reaction was an efficient and simple process to give fl-iodo amines in excellent yields with high chemoselectivity.     

Novel routes to aminophosphonic acids: Interaction of dimethyl H‐phosphonate with hydroxyalkyl carbamates

It was found that the reaction of dimethyl H‐phosphonate ( 1 ) with 2‐hydroxyalkyl‐N‐2′‐hydroxyalkyl carbamates at 135°C includes several chemical reaction steps: (i) chemical transformations of 1‐methyl‐2‐hydroxyethyl‐N‐2′‐hydroxyethyl carbamate ( 2 ) and 2‐methyl‐2‐hydroxyethyl‐N‐2′‐hydroxyethyl carbamate ( 3 ); (ii) transesterification of dimethyl H‐phosphonate with 2 and 3 , and with secondary hydroxyl‐containing compounds that are formed during the course of the chemical transformation of 2‐hydroxyalkyl‐N‐2′‐hydroxyalkyl carbamates; (iii) hydrolysis of 1 and dialkyl H‐phosphonates, formed via transesterification of 1 with secondary hydroxyl‐containing compounds. The interaction was studied by means of ¹H, ¹³C, ³¹P NMR, and FAB mass spectroscopy. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:119–124, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20404     

Acylated Triterpene Saponins from Atroxima liberica Stapf

The four new acylated triterpene saponins 1 – 4 , isolated as two pairs of isomers and named libericosides A₁/A₂ and B₁/B₂, one pair of isomers 5 / 6 , the (Z)‐isomer libericoside C₂ ( 5 ) being new, one new sucrose ester, atroximoside ( 7 ), and eight known compounds were isolated from the roots of Atroxima liberica by repeated MPLC and VLC on normal and reversed‐phase silica gel. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR studies (¹H‐ and ¹³C‐NMR, DEPT, COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry as 3‐O‐β‐D ‐glucopyranosylpresenegenin 28‐{O‐α‐L ‐arabinopyranosyl‐(1→3)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 1 ) and its (Z)‐isomer 2 , 3‐O‐β‐D ‐glucopyranosylpresenegenin 28‐{O‐α‐L ‐arabinopyranosyl‐(1→4)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 3 ) and its (Z)‐isomer 4 , 3‐O‐β‐D ‐glucopyranosylpresenegenin 28‐{O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[6‐O‐acetyl‐β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(Z)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 5 ), and 3‐O‐[(Z)‐feruloyl]‐β‐D ‐fructofuranosyl α‐D ‐glucopyranoside ( 7 ). Compounds 1 – 6 and the known saponins 8 / 9 were evaluated against the human colon cancer cells HCT 116 and HT‐29 and showed moderate to weak cytotoxicity.     

Triumfettamide and Triumfettoside Ic,Two Ceramides and Other Secondary Metabolites from the Stems of Wild Triumfetta cordifolia A. Rich. (Tiliaceae)

Two new ceramides, triumfettamide ( 1 ) and triumfettoside Ic ( 2 ), characterized as (2R,6Z)‐2‐hydroxy‐N‐[(2S,3S,4R)‐1,3,4‐trihydroxyhexacosan‐2‐yl]heptadec‐6‐enamide and (2R)‐N‐{(1S,2R,3E,6Z, 9Z,12Z,15Z)‐1‐[(β‐D ‐glucopyranosyloxy)methyl]‐2‐hydroxyheneicosa‐3,6,9,12,15‐pentaen‐1‐yl}‐2‐hydroxytetradecanamide, respectively, were isolated from the stems of Triumfetta cordifolia A. Rich. besides eight known secondary metabolites identified as heptadecanoic acid, β‐sitosterol glucopyranoside, friedelin, lupeol, betulin, maslinic acid, 2‐hydroxyoleanolic acid and the mixture of stigmasterol and β‐sitosterol. Their structures were determined on the basis of spectroscopic methods as well as HR‐MALDI‐FT‐ICR‐MS analysis, chemical transformation, and by comparison of their physical and spectral data with those reported in the literature and with authentic specimens for some known compounds. Five pentacyclic triterpenoids, friedelin, lupeol, betulin, maslinic acid, and 2‐hydroxyoleanolic acid, have been isolated from Triumfetta genus for the first time.     

Synthesis of 2‐Mercaptobenzaldehyde, 2‐Mercaptocyclohex‐1‐enecarboxaldehydes and 3‐Mercaptoacrylaldehydes

A novel one‐pot approach for the preparation of 2‐mercaptobenzaldehyde, 2‐mercaptocyclohex‐1‐enecarboxaldehydes and 3‐mercaptoacrylaldehydes [(Z)‐3‐mercapto‐2‐methyl‐3‐phenylacrylaldehyde, 3‐mercapto‐3‐(o‐tolyl)acrylaldehyde)] starting from ortho‐bromobenzaldehyde, 2‐chlorocyclohex‐1‐enecarbaldehydes, (Z)‐3‐chloro‐2‐methyl‐3‐phenylacrylaldehyde and 3‐chloro‐3‐(o‐tolyl)acrylaldehyde is reported. The reaction of sulfur with the Grignard reagent of the acetal for the protection of the aldehyde group affords the title compounds through hydrolysis with dilute hydrochloric acid in high yields.