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1.
Enantiomerically pure cis- and trans-5-alkyl-1-benzoyl-2-(tert-butyl)-3-methylimidazolidin-4-ones ( 1, 2, 11, 15, 16 ) and trans-2-(tert-butyl)-3-methyl-5-phenylimidazolidin-4-one ( 20 ), readily available from (S)-alanine, (S)-valine, (S)-methionine, and (R)-phenylglycine are deprotonated to chiral enolates (cf. 3, 4, 12, 21 ). Diastereoselective alkylation of these enolates to 5,5-dialkyl- or 5-alkyl-5-arylimidazolidinones ( 5, 6, 9, 10, 13a-d, 17, 18, 22 ) and hydrolysis give α-alkyl-α-amino acids such as (R)- and (S)-α-methyldopa ( 7 and 8a , resp.), (S)-α-methylvaline ( 14 ), and (R)-α-methyl-methionine ( 19 ). The configuration of the products is proved by chemical correlation and by NOE 1H-NMR measurements (see 23, 24 ). In the overall process, a simple, enantiomerically pure α-amino acid can be α-alkylated with retention or with inversion of configuration through pivaladehyde acetal derivatives. Since no chiral auxiliary is required, the process is coined ‘self-reproduction of a center of chirality’. The method is compared with other α-alkylations of amino acids occurring without racemization. The importance of enantiomerically pure, α-branched α-amino acids as synthetic intermediates and for the preparation of biologically active compounds is discussed. 相似文献
2.
A new route to completely protected α-methylated α-amino acids starting from alanine is described (see Scheme). These derivatives, which are obtained via base-catalyzed opening of the oxazolidinones (2S,4R)- and (2R,4S)- 2 , can be directly employed in peptide synthesis. The synthesis of both enantiomers of Z-protected α-methylaspartic acid β-(tert-butyl)ester (O4-(tert-butyl) hydrogen 2-methylaspartates (R) or (S)- 4a ), α-methyl-glutamic acid γ-(tert-butyl) ester (O5-(tert-butyl) hydrogen 2-methylglutamate (R)- or (S)- 4b ), and of Nε-bis-Boc-protected α-methyllysine (N6,N6-bis[(tert-butyloxy)carbonyl]-2-methyllysine (R)- or (S)- 4c ) is described in full detail. 相似文献
3.
(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 ). 相似文献
4.
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 ). 相似文献
5.
Anastasy О. Kolodiazhna Аleksei I. Skliarov Alena A. Slastennikova 《Phosphorus, sulfur, and silicon and the related elements》2020,195(9):713-717
AbstractAn asymmetric synthesis of (+)- and (–)-methiine (S-methyl-(R)-cysteine sulfoxide) diastereomers has been developed. These natural sulfur compounds were isolated from a variety of Brassica vegetables. As the starting compound, (R)-cysteine was used, which was methylated to form (R)-S-methylcysteine. Then the oxidation of S-methylcysteine with tert-butyl hydroperoxide catalyzed by the chiral tetra(isopropylate)titanium/(S)- or (R)-Binol complex led to the formation of (1?R,2S)-(+)- or (1?R,2R)-(–)-methiin stereomers. 相似文献
6.
The chiral compounds (R)‐ and (S)‐1‐benzoyl‐2,3,5,6‐tetrahydro‐3‐methyl‐2‐(1‐methylethyl)pyrimidin‐4(1H)‐one ((R)‐ and (S)‐ 1 ), derived from (R)‐ and (S)‐asparagine, respectively, were used as convenient starting materials for the preparation of the enantiomerically pure α‐alkylated (alkyl=Me, Et, Bn) α,β‐diamino acids (R)‐ and (S)‐ 11 – 13 . The chiral lithium enolates of (R)‐ and (S)‐ 1 were first alkylated, and the resulting diasteroisomeric products 5 – 7 were aminated with ‘di(tert‐butyl) azodicarboxylate’ (DBAD), giving rise to the diastereoisomerically pure (≥98%) compounds 8 – 10 . The target compounds (R)‐ and (S)‐ 11 – 13 could then be obtained in good yields and high purities by a hydrolysis/hydrogenolysis/hydrolysis sequence. 相似文献
7.
The sodium salts of (S)-alanine, (S)-phenylalanine, (S)-valine, and (S)-methionine are condensed with pivalaldehyde to imines 5 . Cyclization by treatment with benzoyl chloride in cold CH2Cl2 gives mainly (4:1 to > 99:1) the (2S,4S)-4-alkyl-3-benzoyl-2-(tert-butyl)-1,3-oxazolidin-5-ones ( 6 ; cis-configuration) in high yields (85–95%). The oxazolidinones 6 and 7 are deprotonated with lithium diethylamide (LDEA) in tetrahydrofuran (THF) and alkylated (Mel, benzyl bromide) or hydroxyalkylated (benzaldehyde) to 4,4-disubstituted oxazolidinones 9 and 10 , respectively, with high diastereoselectivity (9:1 to 50:1; relative topicity ul). Hydrolysis of three of the oxazolidinones to amino acids of known configuration and optical purity indicates that little if any racemization occurs in the process. 相似文献
8.
The Diels-Alder adduct of furan and 1-cyanovinyl (1′R)-camphanate was converted into methyl [(tert-butyl)-dimethylsilyl 5-deoxy-2, 3-O-isopropylidene-β-L -ribo-hexofuranosid] uronate ((+)- 4 ). Reduction with diisobutyl-aluminium hydride gave the corresponding aldehyde which was condensed with the ylide derived from triphenyl-(propyl)phosphonium bromide to give (1R, 2S, 3S, 4S)-1-[(tert-butyl)dimethylsilyloxy]tetrahedro-2, 3-(isopropyl-idenedioxy)-4-[(Z)-pent-2′ -enyl]furan ((+)- 7 ). Removal of the silyl protective group gave a mixture of the corresponding furanose that underwent Wittig reaction with the ylide derived from [8-(methoxycarbonyl)-octyl]triphenylphosphonium bromide to yield methyl (11R, 12S, 13S, 9Z, 15Z)-13-hydroxy-11, 12-(isopropylidene-dioxy)octadeca-9, 15-dienoate ((?)- 9 ). Acidic hydrolysis, then saponification afforded (11R, 12S, 13S, 9Z, 15Z)-11, 12, 13-trihydroxyoctadeca-9, 15-dienoic acid ( 1 ). 相似文献
9.
Roland A. Obermüller Thomas G. Dax Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》2001,132(9):1057-1062
Summary. When 1-methoxy-2-naphthalene carboxylic acid diethylamide was reacted with tert-butyl lithium in presence of TMEDA and 3,5-dimethoxybenzaldehyde was subsequently added to the reaction mixture, (P, S/M, R)- and (P, R/M, S)-1-tert-butyl-3-((3,5-dimethoxyphenyl)-hydroxymethyl)-naphthalene-2-carboxylic acid diethylamide were formed instead of the corresponding
1-methoxy derivative. The diastereomeric relationship of the products is due to a sterically severely hindered rotation around
the amide-aryl bond.
Received May 11, 2001. Accepted May 18, 2001 相似文献
10.
Roland A. Obermüller Thomas G. Dax Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》2001,5(2):1057-1062
When 1-methoxy-2-naphthalene carboxylic acid diethylamide was reacted with tert-butyl lithium in presence of TMEDA and 3,5-dimethoxybenzaldehyde was subsequently added to the reaction mixture, (P, S/M, R)- and (P, R/M, S)-1-tert-butyl-3-((3,5-dimethoxyphenyl)-hydroxymethyl)-naphthalene-2-carboxylic acid diethylamide were formed instead of the corresponding 1-methoxy derivative. The diastereomeric relationship of the products is due to a sterically severely hindered rotation around the amide-aryl bond. 相似文献
11.
The 1,2,3,4-tetrahydro-N-pivaloyl-isoquinoline-3-carboxylic acids 1d , 2d , and 3d , derived from (R)- or (S)-phenylalanine, (S)-dopa, and (S)-α-methyldopa, respectively, are doubly deprotonated with (tert-butyl)lithium in THF and alkylated at the 1-position (products 5 – 10 ). The major diastereoisomers formed are the result of electrophilic attack from the face opposite to the carboxylate group (rel. topicity ul-1,3). Even the addition to benzaldehyd (→ 7,8 ) is highly stereoselective (one of four diastereoisomers is formed exclusively (300-MHz 1H-NMR analysis)), if MgBr2 etherate is added prior to the electrophile. Some of the obtained amino-acid derivatives are decarboxylated by anodic oxidation in MeOH (→ 11 , 12 , 17 ) and NaBH3CN reduction, and converted to the known 1-methyl- and 1-benzyltetrahydroisoquinolines ( 15 , 16 ) of > 95% ee as well as to the phthalide isoquinoline alkaloid (+)-corlumine of ≥80% ee. The synthetic approach described here is compared with other methods of synthesizing enantiomerically pure 1-substituted tetrahydroisoquinolines (and thus an important group of alkaloids, Scheme 1). 相似文献
12.
M. Vorona I. Potorochina G. Veinberg S. Belyakov I. Shestakova I. Kanepe E. Lukevics 《Chemistry of Heterocyclic Compounds》2009,45(12):1532-1538
The sulfoxide of 6Z-[2-(methoxyimino)propylidene]penicillanic acid tert-butyl ester and the sulfones of 6Z-[2-(hydroxyimino-, methoxyimino-, benzyloxyimino-, 2-bromo- and 4-bromobenzyloxyimino)-propylidene]penicillanic acid in the
syn and anti forms have been synthesized by the condensation of the sulfoxide and sulfone of 6Z-acetylmethylenepenicillanic acid tert-butyl ester with hydroxylamine, methoxyamine, benzyloxyamine, 2-bromo- and 4-bromobenzyloxyamines. The syn and anti isomers
of 3Z-(2-methoxyiminopropylidene)-4R-(benzothiazolyl-2-dithio)-2-oxoazetidinyl-1R-(2-propenyl)acetic acid tert-butyl ester were obtained by opening of the thiazolidine ring in 6Z-[2-(methoxy-imino)propylidene]-1-oxopenicillanic acid tert-butyl ester with 2-mercaptobenzothiazole. The 3Z-(2-methoxyiminopropylidene)-4R-(methylsulfonyl)-2-oxoazetidinyl-1-(2-propylidene)acetic acid tert-butyl ester was synthesized by the interaction of 1,8-diazobicyclo[5.4.0]undec-7-ene and methyl iodide with 6Z-[2-(methoxyimino)propylidene]-1,1-dioxopenicillanic acid tert-butyl ester. A dependence of the cytotoxic effect in relation to cancer and normal cells in vitro on the structure of the
substituent in position 6 and the syn and anti isomerism of the oxyimino group was established for the synthesized compounds. 相似文献
13.
C. G. Overberger John H. Kozlowski 《Journal of polymer science. Part A, Polymer chemistry》1972,10(8):2291-2302
Racemic and optically active hexahydro-5-tert-butoxymethyl-2H-azepin-2-one were polymerized, and the resulting poly-4-tert-butoxymethyl-6-hexanamides were treated to remove the tert-butyl protective group. ORD and CD spectra of (–)-poly-(S)-4-tert-butoxymethyl-6-hexanamide and (–)poly-(S)-4-hydroxymethyl-6-hexanamide were compared with spectra of their low molecular weight models, (S)(–)-6-acetamido-4-tert-butoxymethyl-N-methylhexanamide and (S)( – )-6-acetamido-4-hydroxymethyl-N-methylhexanamide, in 2,2,2-trifluoroethanol, p-dioxane–water mixtures, and methanol–water mixtures. 相似文献
14.
To study the stereoselectivity of enzymatic cleavage of poly(3-hydroxybutyrates) (PHB) in a well-defined system (purified depolymerase and monodisperse substrate of specific relative configuration), linear and cyclic oligomers of HB (OHBs) containing (R)- and (S)-3-hydroxybutanoate residues were synthesized. The starting material (R)-HB was prepared from natural sPHB, and (S)-HB by enantioselective reduction of 3-oxobutanoate with yeast or with H2/Noyori-Taber catalyst (Scheme 2). The HB building blocks were then protected (O-benzyl/tert-butyl ester; Scheme 3) and coupled to give dimers 3 , 4 , tetramers 5 – 9 , and octamers 10 – 18 ; for analytical comparison, a 3mer, 5mer, 6mer, and 7mer ( 19 – 22 ) were also prepared. Two of the tetramers were subjected to macrolactonization conditions (Yamaguchi) to give the cyclic tetramers 23 and 25 and octamers 24 and 26 . All new compounds were fully characterized (m.p., [α]D, CD, IR, 1H- and 13C-NMR, MS, elemental analysis). Single-crystal X-ray structure analyses were performed with oligolides 24 and 25 (Figs. 2 and 4), and the structures, as well as the crystal packing, were compared with those of analogs containing only (R)-HB units or consisting of 3-amino- instead of 3-hydroxybutanoic-acid moieties. 相似文献
15.
Both enantiomers of tert-butyl 2-(tert-butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate ( 11 ; Bbdmoic) were prepared from L -alanine (Schemes 1 and 2). The parent heterocycle, 2-tert-butyl-5,5-dimethylimidazolidin-4-one ( 12 ; from 2-aminoisobutyramide, H-Aib-NH2, and pivalaldehyde) was also available in both enantiomeric forms by resolution with O,O′-dibenzoyltartaric acid. The compound (R)- or (S)- 11 was used as an auxiliary, but also as a chiral Aib building block in a dipeptide synthesis. The 3-propanoyl derivative 13 of (R)- 11 was used for the preparation of enantiomerically pure 2-methyl-3-phenylpropanoic acid (enantiomer ratio (e.r.) 99.5:0.5), by benzylation of the Zn-enolate (→ 14 ; Scheme 3). Oxidative coupling of the bis-enolate derived from heptanedioic acid and (S)- 11 (→ 23 ) and methanolysis of the auxiliary gave dimethyl trans-cyclopentane-1,2-dicarboxylate ( 26 ) with an e.r. of 93:7 (Scheme 5, Fig. 5). The 3-(Boc-Gly)-Bbdmoic derivative 29 was doubly deprotonated and, after addition of ZnBr2 alkylated with alkyl, benzyl, or allyl halides to give the higher amino-acid derivatives with excellent selectivities (e.r. > 99.5:0.5, Schemes 6 and 7). Michael additions of cuprates to [(E)-MeCH?CHCO]-Bbdmoic 36 occurred in high yields, but high diastereoselectivities were only observed with aryl cuprates (diastereoisomer ratio (d.r.) 99:1 for R = Ph, Scheme 8). Finally, 3-(Boc-CH2)-Bbdmoic 17 was alkylated through the ester Li-enolate with primary and secondary alkyl, allyl, and benzyl halides with diastereoselectivities (ds) ranging from 91 to 98%, giving acetals of Boc-Aib-Xxx-O(t-Bu) dipeptides (Scheme 4). The effectiveness of Bbdmoic is compared with that of other chiral auxiliaries previously used for the same types of transformations. 相似文献
16.
Patrice Renaut Jean Millet Christiane Sepulchre Jocelyne Theveniaux Vronique Barberousse Vincent Jeanneret Pierre Vogel 《Helvetica chimica acta》1998,81(11):2043-2052
Mitsunobu displacement of (−)-(1S,4R,5S,6S)-4,5,6-tris{[(tert-butyl)dimethylsilyl]oxy}cyclohex-2-en-1-ol ((−)- 12 ; a (−)-conduritol-F derivative) with 4-ethyl-7-hydroxy-2H-1-benzopyran-2-one ( 16 ) provided a 5a-carba-β-D -pyranoside (+)- 17 that was converted into (+)-4-ethyl-7-[(1′R,4′R,5′S,6′R)-4′,5′,6′-trihydroxycyclohex-2′-en-1′-yloxy]-2H-1-benzopyran-2-one ((+)- 5 ) and (+)-4-ethyl-7-[(1′R,2′R,3′S,4′R)-2′,3′,4′-trihydroxycyclohexyloxy]-2H-1-benzopyran-2-one ((+)- 6 ). The 5a-carba-β-D -xyloside (+)- 6 was an orally active antithrombotic agent in the rat (venous Wessler's test), but less active than racemic carba-β-xylosides (±)- 5 and (±)- 6 . The 5a-carba-β-L -xyloside (−)- 6 was derived from the enantiomer (+)- 12 and found to be at least 4 times as active as (+)- 6 . (+)-4-Cyanophenyl 5-thio-β-L -xylopyranoside ((+)- 3 ) was synthesized from L -xylose and found to maintain ca. 50% of the antithrombotic activity of its D -enantiomer. Compounds (±)- 5 , (±)- 6 , and (−)- 6 are in vitro substrates for galactosyltransferase 1. 相似文献
17.
The title dicarboxylic acid 1d has been prepared in 24% overall yield via, 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalyzed coupling of ethanal and tert-butyl propenoate ( 3 ) to 4 , SN2′-reaction to tert-butyl (Z)-2-romomethyl-2-butenoate ( 5a ), dehydrobrominatin to tert-butyl 2-methylidene-3-butenoate ( 2c ), dimerizatoin to di-tert-butyl 4-vinyl-1-cyclohexene-1,4-dicarboxylate ( 1c ) and acidic ester cleavage. Acidic cleavage of easily obtainable 5a affords (Z)-2-bromomethyl-2-butenoic acid ( 5a ) in 68% yield with respect to ethanal. 相似文献
18.
0The bipyridyl-armed tetra-p-(tert-butyl)calix[4]arenes 1 – 5 were synthesized from tetra-p-(tert-butyl)-calix[4]arene A and 6-(bromomethyl)-6′-methyl-2,2′-bipyridine ( B ) by direct base-strength-driven regioselective O-alkylation or by stepwise procedures. Preliminary complexation studies of the ligands 1 – 3 with CuI affording the complexes 6 – 8 are described. 相似文献
19.
Edith Mrki-Fischer Richard Buchecker Conrad Mans Eugster Gerhard Englert Klaus Noack Max Vecchi 《Helvetica chimica acta》1982,65(7):2198-2211
Absolute Configuration of Antheraxanthin, ‘cis-Aritheraxanthin’ and of the Stereoisomeric Mutatdxanthins The assignement of structure 2 to antheraxanthin (all-E)-(3 S, 5 R, 6 S, 3′ R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol and of 1 to ‘cis-antheraxanthin’ (9Z)-(3 S, 5 R, 6 S, 3′ R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol is based on chemical correlation with (3 R, 3′ R)-zeaxanthin and extensive 1H-NMR. measurements at 400 MHz. ‘Semisynthetic antheraxanthin’ ( = ‘antheraxanthin B’) has structure 6 . For the first time the so-called ‘mutatoxanthin’, a known rearrangement product of either 1 or 2 , has been separated into pure and crystalline C(8)-epimers (epimer A of m.p. 213° and epimer B of m.p. 159°). Their structures were assigned by spectroscopical and chiroptical correlations with flavoxanthin and chrysanthemaxanthin. Epimer A is (3 S, 5 R, 8 S, 3′ R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol ( 4 ; = (8 S)mutatoxanthin) and epimer B is (3 S, 5 R, 8 R, 3′ R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol ( 3 ; = (8 R)-mutatoxanthin). The carotenoids 1 – 4 have a widespread occurrence in plants. We also describe their separation by HPLC. techniques. CD. spectra measured at room temperature and at ? 180° are presented for 1 – 4 and 6 . Antheraxanthin ( 2 ) and (9Z)-antheraxanthin ( 1 ) exhibit a typical conservative CD. The CD. Spectra also allow an easy differentiation of 6 from its epimer 2 . The isomeric (9Z)-antheraxanthin ( 1 ) shows the expected inversion of the CD. curve in the UV. range. The CD. spectra of the epimeric mutatoxanthins 3 and 4 (β end group) are dissimilar to those of flavoxanthin/chrysanthemaxanthin (ε end group). They allow an easy differentiation of the C (8)-epimers. 相似文献
20.
Alaa A.-M. Abdel-Aziz Serry A.A. El Bialy Takehisa Kunieda 《Tetrahedron letters》2004,45(43):8073-8077
An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a,b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1-p-tolylsulfonyl-4,5-di-tert-butyl-2-imidazolidinones 12 and 19 and 1-p-tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20, respectively. Finally, N-p-tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH)2·8H2O to achieve ring cleavage and to provide (1S,2S)-1,2-di-tert-butylethylenediamine 3 and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamine 4. 相似文献