(R)-TTCA·K催化下环己酮与丙烯腈的加成反应

手性催化剂催化下的不对称合成反应是近年来不对称合成研究中受到重视的领域，如在手性催化剂如，在手性冠醚，手性镧配合物、手性硒、手性铑及手性脯氨酸铷盐等催化下，醛、酮与二烃基锌形成手性醇和不对称羟醛缩合反应等，催化下通过Michael加成反应合成手性化合物的方法近年来也有报道，     

A chiral synthesis of four stereoisomers of 1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline, an inducer of Parkinson-like syndrome

Four stereoisomers of 1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline, an inducer of Parkinson-like syndrome, were synthesized by applying a new method of 1,2,3,4-tetrahydroisoquinoline (TIQ) synthesis utilizing the Pummerer reaction as a key step. The chiral centers at C-1 and C-3 were constructed by two routes starting from alaninol (3) and 1-phenylethylamine (4) as a chiral source. Enantiomerically pure 1,3-dimethyl-TIQs (1R,3S)-(2) [corrected], (1S,3R)-(ent-2) [corrected], (1S,3S)-(1) [corrected], and (1R,3R)-(ent-1) [corrected] were prepared in a stereochemically unambiguous manner from 3 in 11 steps (route I) and from 4 in 6 steps (route II). The conformations of tetrahydroisoquinoline ring in 1-methyl, 3-methyl, and 1,3-dimethyl-TIQs were discussed on the basis of their CD, 1H-NMR spectra, and steric energies.     

Asymmetric strecker synthesis of alpha-amino acids via a crystallization-induced asymmetric transformation using (R)-phenylglycine amide as chiral auxiliary

[reaction: see text]. Diastereoselective Strecker reactions based on (R)-phenylglycine amide as chiral auxiliary are reported. The Strecker reaction is accompanied by an in situ crystallization-induced asymmetric transformation, whereby one diastereomer selectively precipitates and can be isolated in 76-93% yield and dr > 99/1. The diastereomerically pure alpha-amino nitrile obtained from pivaldehyde (R1 = t-Bu, R2 = H) was converted in three steps to (S)-tert-leucine in 73% yield and >98% ee.     

Facile route to 3,5-disubstituted morpholines: enantioselective synthesis of O-protected trans-3,5-bis(hydroxymethyl)morpholines

[reaction: see text] (3R,5R)-1 R1 & R2 = TBDPS, (3S,5R)-2 R1 = Bn,R2 = TBDPS, (3S,5S)-3 R2 & R2 = Bn. trans-3,5-Bis(benzyl/tert-butyldiphenylsilyloxymethyl)morpholines, promising candidates for the C(2)-symmetric class of chiral reagents, were prepared with excellent optical purity. A key step in the synthesis is the coupling of a serinol derivative with 2,3-O-isopropylideneglycerol triflate or its equivalent. This methodology was extended to the synthesis of chiral trans-3-(benzyloxymethyl)-5-(tert-butyldiphenylsilyloxymethyl)morpholine, a potentially useful chiral building block.     

Enantioselective synthesis of ansa-zirconocenes

The reaction of the chiral chelated bis-amide complex Zr{(2R,4R)-PhNCHMeCH2CHMeNPh}Cl2(THF)2 (R,R-7) with lithium ansa-bis-indenyl reagents Li2[SBI](Et2O) (8a, SBI = (1-indenyl)2SiMe2) or Li2[EBI](Et2O) (8b, EBI = 1,2-(1-indenyl)2ethane) in THF affords the corresponding ansa-zirconocenes S,S-(SBI)Zr{(2R,4R)-PhNCHMeCH2CHMeNPh} (S,S,R,R-9a) or S,S-(EBI)Zr{(2R,4R)-PhNCHMeCH2CHMeNPh} (S,S,R,R-9b) in >95% isolated yield and >99% enantiomeric excess. Compound 9b was converted to the corresponding enantiomerically pure dichloride S,S-(EBI)ZrCl2 (S,S-10b) in 91% isolated yield by reaction with HCl in Et2O. The chiral diamine (2R,4R)-HPhNCHMeCH2CHMeNHPh (R,R-5) was recovered from this reaction.     

Dioxomolybdenum(VI) Complexes with New Enantiomerically Pure Amino Diol Ligands

(R)-Phenylglycinol is shown to be an efficient building block for the synthesis of chiral amino diols in pure diastereomeric form by epoxide ring-opening reactions. The reaction with rac-trans-stilbene oxide gives [HOCH(2)-(R)-PhCH]NH[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-HNO(2)H(2)] in 32% yield, which can be methylated at nitrogen to give enantiomerically pure [HOCH(2)-(R)-PhCH]NCH(3)[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-MeNO(2)H(2)]. These amino diol ligands have been used to prepare chiral dioxomolybdenyl complexes of the formula N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) (1) and N(R)-2(R)-3(R)-4(S)-(MeNO(2))MoO(2) (2). The absolute configuration at each stereocenter in the Mo(VI) complexes has been established by (1)H NOESY spectroscopy. The configuration determined for 1 has been confirmed by an X-ray analysis. Crystal data: orthorhombic P2(1)2(1)2(1), a =7.620(3), b = 13.589(2), c = 20.339(3) ?, Z = 4, R = 0.0336. The structure consists of a polymeric chain of N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) molecules connected through unsymmetrical Mo=O --> Mo bridges. Each metal center is coordinated in a distorted octahedral geometry by a cis dioxo unit and by two trans alkoxo atoms. The coordination polyhedron is completed by a nitrogen atom and by a bridging oxo oxygen atom from an adjacent molecule. Compound 2 catalyzes the oxidation of PPh(3) to OPPh(3) by DMSO through a mechanism that involves the intermediacy of a Mo(IV) species.     

Designer chiral quaternary ammonium bifluorides as an efficient catalyst for asymmetric nitroaldol reaction of silyl nitronates with aromatic aldehydes

Designer chiral quaternary ammonium bifluoride 1 has been prepared, and both its catalytic and its chiral efficiency have been clearly demonstrated by achieving the first catalytic asymmetric nitroaldol reaction of silyl nitronate with aldehydes. For instance, the reaction of trimethylsilyl nitronate 2 (R(1) = Me) with benzaldehyde (R(2) = Ph) in THF in the presence of (S,S)-1 (2 mol %) proceeded smoothly at -78 degrees C, giving the corresponding nitroaldol adduct 3 (R(1) = Me, R(2) = Ph) in 92% isolated yield (anti/syn = 92:8) with 95% ee (anti isomer). The method was found to be successfully applicable to other aromatic aldehydes and silyl nitronates, and a high level of anti selectivity and enantiomeric excess was constantly observed. This finding should lead to the further development of fluoride ion-catalyzed asymmetric carbon-carbon bond-forming reactions.     

5-L-孟氧基4-苄氨基丁烯内酯的不对称合成和晶体结构研究

温和条件下,苄胺与手性合成子5-(L)-孟氧基3-溴-2(5)呋喃酮通过串联的不对称迈克尔加成/分子内消除反应合成了一种新手性化合物:5-L-孟氧基-4-苄胺基丁烯内酯。产物经过IR、1H-NMR、MS谱学表征,并经X-ray单晶衍射测定了其结构。新化合物属于正交晶系,P212121空间群,a=5.2945(4),b=14.2829(10),c=26.0769(18),Mr=343.45,Z=4,V=1972.0(2)3,Dc=1.157g/cm3,μ(MoKα)=0.076mm-1,F(000)=744,R=0.0387,wR=0.0880。     

(+)-(1S,2S,5R)-8-联苯薄荷醇的合成

以(R)-( )-pu legone为起始原料,经1,4-加成,还原两步反应合成了手性辅助试剂( )-(1S,2S,5R)-8-联苯薄荷醇及其差向异构体(-)-(1R,2S,5R)-8-联苯薄荷醇,总产率95%。其结构经1H NMR,13C NMR,IR,MS和X-射线衍射仪表征。     

Stereoselective synthesis of optically active disilanes and selective functionalization by the cleavage of silicon-naphthyl bonds with bromine

Optically active disilanes with one chiral silicon center, (R)-1,2-dimethyl-1-(naphth-1-yl)-1,2,2-triphenyldisilane and (R)-1,2,2-trimethyl-2-(4-methoxynaphth-1-yl)-1-(naphth-1-yl)-1-phenyldisilane, were obtained by the reaction of (S)-methyl(naphth-1-yl)phenylchlorosilane (> 99% ee) with methyldiphenylsilyllithium or by the reaction of methyldiphenylchlorosilane with optically active (S)-methyl(naphth-1-yl)phenylsilyllithium and by the reaction of (S)-methyl(naphth-1-yl)phenylchlorosilane (> 99% ee) with dimethyl(4-methoxynaphth-1-yl)silyllithium. Under the optimized conditions, the reactions proceeded with almost complete inversion for the cholorosilanes and retention for the silyl anions. Optically active disilanes with two chiral centers, (1R,2R)-1,2-dimethyl-1,2-di(naphth-1-yl)-1,2-diphenyldisilane and (1S,2S)-1,2-di(4-methoxynaphth-1-yl)-1,2-dimethyl-1,2-diphenyldisilane, were obtained in high optical purity by the reactions of corresponding optically active halogenosilanes (Cl or F) with optically active silyllithiums. The silicon-silicon bond and the silicon-naphthyl bond of (R)-1,1,2-trimethyl-1,2-di(naphth-1-yl)-2-phenyldisilane and (1R,2R)-1,2-dimethyl-1,2-di(naphth-1-yl)-1,2-diphenyldisilane were cleaved without selectivity on bromination. The silicon-(4-methoxynaphth-1-yl) bond of (R)-1,2,2-trimethyl-2-(4-methoxynaphth-1-yl)-1-(naphth-1-yl)-1-phenyldisilane was regiospecifically cleaved, followed by the stereoselective cleavage of the remaining chiral silicon-naphthyl bond (94% inversion). Although the silicon-(4-methoxynaphth-1-yl) bonds of (1S,2S)-1,2-di(4-methoxynaphth-1-yl)-1,2-dimethyl-1,2-diphenyldisilane (> 99% ee) were regioselectively cleaved without silicon-silicon bond scission, remarkable racemization could not be avoided during the one-pot reaction.     

Biomimetic iron-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide

A novel and general biomimetic non-heme Fe-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide is reported herein. The catalyst consists of ferric chloride hexahydrate (FeCl(3)6 H(2)O), pyridine-2,6-dicarboxylic acid (H(2)(pydic)), and readily accessible chiral N-arenesulfonyl-N'-benzyl-substituted ethylenediamine ligands. The asymmetric epoxidation of styrenes with this system gave high conversions but poor enantiomeric excesses (ee), whereas larger alkenes gave high conversions and ee values. For the epoxidation of trans-stilbene (1 a), the ligands (S,S)-N-(4-toluenesulfonyl)-1,2-diphenylethylenediamine ((S,S)-4 a) and its N'-benzylated derivative ((S,S)-5 a) gave opposite enantiomers of trans-stilbene oxide, that is, (S,S)-2 a and (R,R)-2 a, respectively. The enantioselectivity of alkene epoxidation is controlled by steric and electronic factors, although steric effects are more dominant. Preliminary mechanistic studies suggest the in situ formation of several chiral Fe-complexes, such as [FeCl(L*)(2)(pydic)]HCl (L*=(S,S)-4 a or (S,S)-5 a in the catalyst mixture), which were identified by ESIMS. A UV/Vis study of the catalyst mixture, which consisted of FeCl(3)6 H(2)O, H(2)(pydic), and (S,S)-4 a, suggested the formation of a new species with an absorbance peak at lambda=465 nm upon treatment with hydrogen peroxide. With the aid of two independent spin traps, we could confirm by EPR spectroscopy that the reaction proceeds via radical intermediates. Kinetic studies with deuterated styrenes showed inverse secondary kinetic isotope effects, with values of k(H)/k(D)=0.93 for the beta carbon and k(H)/k(D)=0.97 for the alpha carbon, which suggested an unsymmetrical transition state with stepwise O transfer. Competitive epoxidation of para-substituted styrenes revealed a linear dual-parameter Hammett plot with a slope of 1.00. Under standard conditions, epoxidation of 1 a in the presence of ten equivalents of H(2) (18)O resulted in an absence of the isotopic label in (S,S)-2 a. A positive nonlinear effect was observed during the epoxidation of 1 a in the presence of (S,S)-5 a and (R,R)-5 a.     

Direct synthesis of NNN-donor enantiopure scorpionate ligands by an efficient diastereoselective nucleophilic addition to imines

New enantiopure imines (1-9) with a chiral substrate to control the stereochemistry of a newly created stereogenic center have been synthesized by reaction of the commercially available (1R)-(-)-myrtenal and different primary amines. The diastereomerically enriched lithium-scorpionate compounds [Li(κ(3)-mobpza)(THF)] (10) (mobpza = N-p-methylphenyl-(1R and 1S)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethylamide), [Li(κ(3)-mobpza)(THF)] (11) (mobpza = N-p-methoxyphenyl-(1R and 1S)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethylamide), [Li(κ(3)-fbpza)(THF)] (12) (fbpza = N-p-fluorophenyl-(1R and 1S)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethylamide), and [Li(κ(3)-clbpza)(THF)] (13) (clbpza = N-p-chlorophenyl-(1R and 1S)-1-[(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl]-2,2-bis(3,5-dimethylpyrazol-1-yl)ethylamide) were obtained by a diastereoselective 1,2-addition of an organolithium reagent to imines in good yield and with good diastereomeric excess (ca. 80%). The complexes [LiCl(κ(2)-R,R-fbpzaH)(THF)] (14) and [LiCl(κ(2)-R,R-clbpzaH)(THF)] (15) were obtained in enantiomerically pure form by the treatment of THF solutions of 12 or 13 with NH(4)Cl. The enantiomerically pure amines (R,R-mbpzaH) (16), (R,R-mobpzaH) (17), (R,R-fbpzaH) (18), and (R,R-clbpzaH) (19) were obtained by hydrolysis of the lithium-scorpionate compounds 10-13 with H(2)O. The lithium compound 12 was reacted with [TiCl(4)(THF)(2)] or [ZrCl(4)] to give the enantiopure complexes [MCl(3)(κ(3)-R,R-fbpza)] [M = Ti (20), Zr (21)]. The amine compound 18 reacted with [MX(4)] (M = Ti, X = O(i)Pr, OEt; M = Zr; X = NMe(2)) to give the complexes [MX(3)(κ(3)-R,R-fbpza)] (22-24). The reaction of Me(3)SiCl with [Zr(NMe(2))(3)(κ(3)-R,R-fbpza)] (24) in different molar ratios led to the halide-amide-containing complexes [ZrCl(NMe(2))(2)(κ(3)-R,R-fbpza)] (25) and [ZrCl(2)(NMe(2))(κ(3)-R,R-fbpza)] (26) and the halide complex 21. The isolation of only one of the three possible diastereoisomers of complexes 25 and 26 revealed that chiral induction from the ligand to the zirconium center took place. The structures of these compounds were elucidated by (1)H and (13)C{(1)H} NMR spectroscopy, and the X-ray crystal structures of 5, 12, 14, 15, and 24 were also established.     

Chiral alpha-branched benzylic carbocations: diastereoselective intermolecular reactions with arene nucleophiles and NMR spectroscopic studies

The chiral benzylic alcohols 1-6 were prepared and subjected to S(N)1-type displacement reactions with various arene nucleophiles in acidic medium. Under optimized conditions (HBF(4).OEt(2), CH(2)Cl(2), -78 degrees C --> r.t.) the corresponding 1,1-diarylalkanes 11-18 and 20 were obtained in good chemical yields (48-99%). The facial diastereoselectivity of the reaction is high (d.r. = 91/9-97/3) when the substrate bears a stereogenic carbon center -CHtBuMe in the alpha-position to the electrophilic carbon atom. If the starting material was enantiomerically pure, no significant racemization was observed (94% ee --> 92% ee). The reactions proceed stereoconvergently as demonstrated by the conversion of the separated diastereoisomers syn-1a and anti-1a in separate reactions to the same product syn-11 (d.r. = 97/3). Further evidence for long-lived chiral benzylic carbocations as reaction intermediates was obtained from NMR studies in superacidic medium. The chiral cation 24 was generated in SO(2)ClF as the solvent at -70 degrees C employing SbF(5) as the Lewis acid and characterized by its (1)H and (13)C NMR spectra. NOE measurements suggest a preferred conformation in which the diastereotopic faces of the cation are differentiated by the two carbon substituents R and Me at the stereogenic carbon center in the alpha-position. The hypothesis is further supported by the observation that the diastereoselectivity of the substitution reaction decreases if the bulky tert-butyl (R = tBu) substituent in the substrate 1a is replaced by a smaller ethyl group (2a, R = Et).     

Asymmetric allylic substitution catalyzed by C1-symmetrical complexes of molybdenum: structural requirements of the ligand and the stereochemical course of the reaction

Application of new chiral ligands (R)-(-)-12 a and (S)-(+)-12 c (VALDY), derived from amino acids, to the title reaction, involving cinnamyl (linear) and isocinnamyl (branched) type substrates (4 and 5 --> 6), led to excellent regio- and enantioselectivities (>30:1, < or =98 % ee), showing that ligands with a single chiral center are capable of high asymmetric induction. The structural requirements of the ligand and the mechanism are discussed. The application of single enantiomers of deuterium-labeled substrates (both linear 38 c and branched 37 c) and analysis of the products (41-43) by (2)H{(1)H} NMR spectroscopy in a chiral liquid crystal matrix allowed the stereochemical pathways of the reaction to be distinguished. With ligand (S)-(+)-12 c, the matched enantiomer of branched substrate was found to be (S)-5, which was converted into (R)-6 with very high regio- and stereoselectivity via a process that involves net retention of stereochemistry. The mismatched enantiomer of the branched substrate was found to be (R)-5, which was also converted into (R)-6, that is, with apparent net inversion, but at a lower rate and with lower overall enantioselectivity. This latter feature, which may be termed a "memory effect", reduced the global enantioselectivity in the reaction of the racemic substrate (+/-)-5. The stereochemical pathway of the mismatched manifold has been shown also to be one of net retention, the apparent inversion occurring through equilibration via an Mo-allyl intermediate prior to nucleophilic attack. Incomplete equilibration leads to the memory effect and thus to lower enantioselectivity. Analysis of the mismatched manifold over the course of the reaction revealed that the memory effect is progressively attenuated with the nascent global selectivity increasing substantially as the reaction proceeds. The origin of this effect is suggested to be the depletion of CO sources in the reaction mixture, which attenuates turnover rate and thus facilitates greater equilibrium. The linear substrate was also converted into the branched product with net syn stereochemistry, as shown by isotopic labeling. An analogous process operates in the generation of small quantities of linear product from branched substrate.     

Diastereomer method for determining ee by (1)H NMR and/or MS spectrometry with complete removal of the kinetic resolution effect

[structure: see text] Using chiral auxiliaries, 2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid) (S)-(+)-1 and its deuterium-labeled enantiomer (R)-(-)-1-d(n)() (n = 3 or 6), we have developed a new diastereomer method for determining enantiomeric excess (% ee) of chiral alcohols by (1)H NMR and/or MS spectrometry, where the kinetic resolution effect is completely excluded. The data of % ee determined by this method agree well with those calculated by weight, the average error being ca. +/-1.08% ee.     

手性金属簇合物的合成、结构表征及其反应

用潜手性羰基簇合物 ( μ3 S)RuCo2 (CO) 9( 1 )与阴离子金属交换试剂Na[M (CO) 3C5 H4C(O)R][R =H ,CH3,C6 H5 ,C6 H4C(O)OCH3;M =Mo ,W ]在四氢呋喃中回流反应 ,生成一系列新的由四个不同原子组成的不对称四面体簇合物 ( μ3 S)RuCoM (CO ) 8CpCOR .研究了簇合物 ( μ3 S)RuCoMo(CO) 8CpCOCH3的还原反应 .对合成的所有化合物进行了IR、1HNMR、C/H元素分析 ,测定了簇合物( μ3 S)RuCoMo(CO) 8CpCOC6 H5 的单晶结构 .     

手性高效液相色谱拆分3-取代异吲哚-1-酮的研究

从伏牛花类植物中提取的生物碱Lennoxam ine^[1]、Nuevam ine和Chilenine,新研发的抗焦虑药Paz-inaclone^[2]和Pagoclone^[3]以及利尿、抗高血压药Chlortalidone^[4]等均含有光活性3-取代异吲哚-1-酮(2,3-二氢-1H -异吲哚-1-酮).这类化合物还是一类新型的不对称合成手性辅助基^[5].因此,光学纯的3-取代异吲哚-1-酮化合物在药物研发和不对称合成等领域具有应用前景.但有关它们的色谱拆分少见报道^[6,7].本文对15个外消旋3-取代异吲哚-1-酮样品进行高效液相色谱拆分研究,通过建立的手性色谱方法,不仅准确测定了相关产物的光学纯度,而且确认了N -取代邻苯二甲酰亚胺上手性辅助基在不对称合成过程^[8]中未发生消旋化.同时探讨了样品中3-位取代基对手性拆分的影响.     

Asymmetric hydrosilylation of styrenes catalyzed by palladium-MOP complexes: ligand modification and mechanistic studies

In the palladium-catalyzed asymmetric hydrosilylation of styrene (3a) with trichlorosilane, several chiral monophosphine ligands, (R)-2-diarylphosphino-1,1'-binaphthyls (2a-g), were examined for their enantioselectivity. The highest enantioselectivity was observed in the reaction with (R)-2-bis[3,5-bis(trifluoromethyl)phenyl]phosphino-1,1'-binaphthyl (2g), which gave (S)-1-phenylethanol (5a) of 98% ee after oxidation of the hydrosilylation product, 1-phenyl-1-(trichlorosilyl)ethane (4a). The palladium complex of 2g also efficiently catalyzed the asymmetric hydrosilylation of substituted styrenes on the phenyl ring or at the beta position to give the corresponding chiral benzylic alcohols of over 96% ee. Deuterium-labeling studies on the hydrosilylation of regiospecifically deuterated styrene revealed that beta-hydrogen elimination from 1-phenylethyl(silyl)palladium intermediate is very fast compared with reductive elimination giving hydrosilylation product when ligand 2g is used. The reaction of o-allylstyrene (9) with trichlorosilane catalyzed by (R)-2g/Pd gave (1S,2R)-1-methyl-2-(trichlorosilylmethyl)indan (10) (91% ee) and (S)-1-(2-(propenyl)phenyl)-1-trichlorosilylethanes (11a and 11b) (95% ee). On the basis of their opposite configurations at the benzylic position, a rationale for the high enantioselectivity of ligand 2g is proposed.     

Enantioselective total syntheses of the Ipecacuanha alkaloid emetine, the Alangium alkaloid tubulosine and a novel benzoquinolizidine alkaloid by using a domino process

The first enantioselective syntheses of the Ipecacuanha alkaloid emetine (1) and the Alangium alkaloid tubulosine (2) is described employing a domino Knoevenagel/hetero-Diels-Alder reaction and an enantioselective catalytic transfer hydrogenation of imines as key steps. Thus, hydrogenation of the imine 15 with the catalyst (R,R)-16 gives the tetrahydroisoquinoline 14 with 95 % ee which was transformed into the aldehyde (1S)-7. The three-component domino reaction of (1S)-7 with 6 and 8 led to 19, which in a second domino process was treated with K(2)CO(3) in methanol followed by a hydrogenation to give the benzoquinolizidine 4 together with the diastereomers 22 and 23 in a overall yield of 66 %. Further transformation of 4 with the amines 3 and 5 yielded enantiopure emetine (1) and tubulosine (2), respectively. In addition, starting from 19 the novel benzoquinolizidine alkaloid 34 was synthesised; this compound resembles the vallesiachotamine alkaloid dihydroantirhin 31, which has not been isolated so far but probably must also exist in nature.     

Asymmetric PTC C-alkylation catalyzed by chiral derivatives of tartaric acid and aminophenols. Synthesis Of (R)- and (S)-alpha-methyl amino acids

A new type of efficient chiral catalyst has been elaborated for asymmetric C-alkylation of CH acids under PTC conditions. Sodium alkoxides formed from chiral derivatives of tartaric acid and aminophenols (TADDOL's 2a-e and NOBIN's 3a-h) can be used as chiral catalysts in the enantioselective alkylation, as exemplified by the reaction of Schiff's bases 1a-e derived from alanine esters and benzaldehydes with active alkyl halides. Acid-catalyzed hydrolysis of the products formed in the reaction afforded (R)-alpha-methylphenylalanine, (R)-alpha-naphthylmethylalanine, and (R)-alpha-allylalanine in 61-93% yields and with ee 69-93%. The procedure could be successfully scaled up to 6 g of substrate 1b. When (S,S)-TADDOL or (R)-NOBIN are used, the (S)-amino acids are formed. A mechanism rationalizing the observed features of the reaction has been suggested.