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1.
Dixon DJ  Horan RA  Monck NJ  Berg P 《Organic letters》2004,6(24):4427-4429
The camphor-derived tetrahydropyran (camTHP*)-desymmetrized glycinamide 1 undergoes efficient and highly diastereoselective lithium enolate Michael additions to nitro olefins, alpha,beta-unsaturated ketones, esters, and lactones. Straightforward manipulation of these products affords 3-substituted pyroglutamides and beta-aryl-alpha,gamma-diamino acid derivatives, highlighting the ease of synthesis of enantiomerically enriched, functionally dense molecules using this novel building block. [reaction: see text]  相似文献   

2.
Addition of Et(2)AlCN and i-PrOH to ketosulfinimines (N-sulfinyl imines) affords corresponding alpha-alkyl alpha-amino nitriles in moderate to good yields. The diastereoselectivity is largely dependent on the E/Z isomer ratio of the ketosulfinimine. Hydrolysis of the diastereomerically pure amino nitriles affords enantiopure alpha-alkyl alpha-amino acids in moderate to good yields.  相似文献   

3.
Wang H  Zhao X  Li Y  Lu L 《Organic letters》2006,8(7):1379-1381
[reaction: see text] Stereoselective approaches to alpha-trifluoromethylated alpha-amino acids (alpha-Tfm AAs) have been developed. The stereoconfigurations of the resulting alpha-Tfm AA precursors were well controlled by using different solvents. The optically active (S)-2-amino-2-phenyl-1,1,1-trifluoropropanoic acid was synthesized by this method.  相似文献   

4.
A Passerini condensation of acyl cyanides, carboxylic acids, and isonitriles has been developed that affords efficient access to functionalized diamides as well as beta-peptides of alpha-hydroxy-beta-amino acids. Such compounds are protease-resistant and form stable helical and sheet structures when incorporated into larger peptides. N-Protected alpha-amino acids and isocyanoesters derived from alpha-amino acids participate in the condensation, leading to alpha/beta peptides embodying the heterogeneous alpha/beta/alpha backbone motif, recent examples of which display antibiotic activity.  相似文献   

5.
[reaction: see text] N-Sulfinyl alpha-amino 1,3-dithioketals are prepared in high de and good yield by treating sulfinimines with lithio-1,3-dithianes. Selective removal of the N-sulfinyl or the thioketal groups affords stable alpha-amino 1,3-dithioketals and N-sulfinyl alpha-amino ketones, respectively. This new sulfinimine-derived chiral building block is employed in the asymmetric synthesis of polyoxypeptin amino acid (2S,3R)-(-)-3-hydroxy-3-methylproline.  相似文献   

6.
In our previous work a new method for the cross-linking of protein was proposed. The method is based on the spontaneous chelate formation process between salicylaldehyde and alpha-amino acid residues. Thus, the facile procedure for the introduction of these residues into protein is required. In this paper, a modification reagent which affords gamma-glutamylation products, i.e., introducing an alpha-amino acid functional group to the protein was proposed. Versatility of the reagent for the preparation of a cross-linked enzyme was examined.  相似文献   

7.
Cross-coupling of aromatic aldehydes or benzoins with unactivated imines catalyzed by an N-heterocyclic carbene (NHC) affords alpha-amino ketones smoothly.  相似文献   

8.
A simple method for preparation of fluoroalkyl beta-enaminophosphonates 1 from alkylphosphonates 2 and perfluoroalkyl nitriles 3 is reported. Olefination reaction of functionalized phosphates 1 with aldehydes gives alpha,beta-unsaturated imines 5. Acid hydrolysis of these fluoroalkyl derivatives 5 affords alpha,beta-unsaturated ketones 6, while their selective reduction with hydrides leads to the formation of allylamines 7, enamines 8, and saturated ketones 9 or amines 10. Selective oxidative cleavage of the carbon-carbon double bond of allylamines 7 gives fluorinated alpha-amino aldehydes 12, alpha-amino ketones 13, or alpha-amino acid derivatives 14.  相似文献   

9.
Five-, six-, and seven-membered cyclic alpha-amino phosphonates, amino acid surrogates, are prepared in enantiomerically pure form via the highly diastereomeric addition of metal phosphonates to masked oxo sulfinimines. Hydrolysis of the resulting masked oxo alpha-amino phosphonates followed by reduction of the intermediate cyclic imino phosphonates affords the title compounds in good yield.  相似文献   

10.
Ohno H  Hamaguchi H  Tanaka T 《Organic letters》2000,2(14):2161-2163
Treatment of 3-alkyl-2-ethynylaziridines with InI in the presence of Pd(PPh(3))(4) and H(2)O gave allenylindium reagents bearing a protected amino group in high yields. Stereoselective addition of the allenylindium to aldehydes affords 2-ethynyl-1,3-amino alcohols bearing three chiral centers in good yields.  相似文献   

11.
The addition of potassium dialkyl phosphites to enantiopure O-protected alpha-hydroxy sulfinimine pseudoenantiomers affords beta-hydroxy alpha-amino phosphonates in good yield and de. The reaction exhibits a strong match-mismatch effect.  相似文献   

12.
We report the application of "click" chemistry for the synthesis of hybrid calixarenes appended on the upper rim with carbohydrate and N,C-protected alpha-amino acids. The chemoselective N- or C-deprotection of the alpha-amino acids and their subsequent transformation into dipeptides is described. The first example of a chemo-enzymatic synthesis on upper rim derived calix[4]arenes using trans-sialidase affords sialylated lactose calix[4]arenes. Our innovative chemo-enzymatic process paves the way for further applications.  相似文献   

13.
A practical synthesis for the preparation of a diverse series of cyclopropane alpha-amino acids is described. Nitrocyclopropane carboxylates can be readily prepared through treatment of alpha-nitroesters and iodobenzene diacetate or alpha-nitro-alpha-diazoesters with a Rh(II) catalyst and an olefin. Reduction of the nitro group using zinc/HCl in i-PrOH affords substituted cyclopropane alpha-amino esters in modest to high yields (54-99%). A "one-pot" procedure involving sequential cyclopropanation and reduction is described. The method can also be applied to the preparation of arylcyclopropyl amines (three examples).  相似文献   

14.
5,6-Dihydropyridine-2-thiones 2 are synthesized from 5,6-dihydropyridin-2-ones 1 and Lawesson reagent. Stereoselective Michael-like addition of amines, methylhydrazine or functionalized thiols affords trans piperidine-2-thiones 5 with the corresponding heterosubstituent in position 4 as major products. The configuration of the adducts 5 was determined by nmr-techniques.  相似文献   

15.
[reaction: see text] Convenient conditions are described for the transformation of alpha-aminonitriles to the tetrazole analogues of alpha-amino acids. Refluxing the starting material in water/2-propanol at 80 degrees C with sodium azide and catalytic zinc bromide affords the tetrazole product in yields generally exceeding 90%.  相似文献   

16.
[reaction: see text] L-Proline-catalyzed direct asymmetric Mannich reactions of N-PMP protected alpha-imino ethyl glyoxylate with various alpha,alpha-disubstituted aldehydes affords quaternary beta-formyl alpha-amino acid derivatives with excellent yields and enantioselectivities. The Mannich products are further converted to the corresponding quaternary alpha- and beta-amino acids and beta-lactams.  相似文献   

17.
An efficient synthesis of 1-azadienes derived from alpha-aminoesters is achieved through an aza-Wittig reaction of phosphazenes with beta,gamma-unsaturated alpha-ketoesters. Regioselective 1,2-reduction of these functionalized 1-azadienes affords vinylglycine derivatives, while conjugative 1,4-reduction gives alpha-dehydroamino acid compounds. Reduction of both the carbon-carbon and the imine-carbon-nitrogen double bonds leads to the formation of alpha-amino acid derivatives.  相似文献   

18.
[reaction: see text] In the presence of nucleophiles, Lewis acid mediated cleavage of alpha-amino ethers derived from quincorine and quincoridine affords a variety of C2-substituted and C6-vinylated 1-azabicyclo[3.2.2]nonanes. These are enantiopure and are formed in S(N)1-like reactions with complete stereocontrol. There is no leakage into 2-Nu en route to product 1-Nu or vice versa. Me(3)SiCN provides new Strecker-type alpha-amino nitriles. In the presence of TTMPP-BF(3).OEt(2), the ketene acetal Me(2)C=C(OMe)OSiMe(3) delivers enantiopure bicyclic beta-amino acid esters.  相似文献   

19.
Versatile electrophiles N-acylhydrazones are synthesized via diazotization, reduction, and acylation of alpha-amino acid esters. Reduction of diazo esters with L-selectride or tributylphosphine affords the corresponding hydrazones in good yields. Both reducing agents give anti-hydrazones as the major product although the reactivity of each reductant is slightly different. The resulting hydrazones are acylated to give N-acylhydrazones, which are subjected to further reactions to give 1,3,4-oxadiazin-6-ones that serve as useful synthetic intermediates for the Diels-Alder reaction.  相似文献   

20.
An acid-stable hydride complex [Cp*IrIII(bpy)H]+ {1, Cp* = eta5-C5Me5, bpy = 2,2'-bipyridine} serves as the active catalyst for the highly chemoselective synthesis of alpha-amino acids by reductive amination of alpha-keto acids with aqueous NH3 and HCOO- in water at pH 5-8. pH-dependent catalytic 15N- and 2H-double-labeling has also been accomplished by using 15NH3 and DCOONa, which are ideal amine and hydride ion sources, respectively.  相似文献   

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