New routes to 1,4- benzodiazepin-2,5-diones

Akssira, Mohamed; Boumzebra, M.; Kasmi, H.; Dahdouh, A.; Roumestant, M. L.; Viallefont, Ph.

doi:10.1016/s0040-4020(01)85371-0

Cited by 42 publications

(29 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Anhydrous dimethylformamide (DMF), dimethyl sulfoxide (DMSO), hexane, and tetrahydrofuran (THF) were purchased from Aldrich or Sigma and used under an argon atmosphere. Spectra/Por molecular porous membrane (molecular weight cutoff = 3500) was purchased from Spectrum Laboratories, Inc. β‐Benzyl‐ L ‐glutamate N ‐carboxyanhydride (BLG‐NCA) was synthesized from N ‐ tert ‐butyloxycarbonyl‐γ‐benzyl L ‐glutamic acid and phosphorus trichloride, as detailed elsewhere,27 and was recrystallized twice from THF/hexane (85% yield).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and properties of biomimetic poly(L‐glutamate)‐b‐poly(2‐acryloyloxyethyllactoside)‐b‐poly(L‐glutamate) triblock copolymers

Dong

Faucher

Chaikof

2004

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

A novel class of biomimetic glycopolymer–polypeptide triblock copolymers [poly(L‐glutamate)–poly(2‐acryloyloxyethyllactoside)–poly(L‐glutamate)] was synthesized by the sequential atom transfer radical polymerization of a protected lactose‐based glycomonomer and the ring‐opening polymerization of β‐benzyl‐L‐glutamate N‐carboxyanhydride. Gel permeation chromatography and nuclear magnetic resonance analyses demonstrated that triblock copolymers with defined architectures, controlled molecular weights, and low polydispersities were successfully obtained. Fourier transform infrared spectroscopy of the triblock copolymers revealed that the α‐helix/β‐sheet ratio increased with the poly(benzyl‐L‐glutamate) block length. Furthermore, the water‐soluble triblock copolymers self‐assembled into lactose‐installed polymeric aggregates; this was investigated with the hydrophobic dye solubilization method and ultraviolet–visible analysis. Notably, this kind of aggregate may be useful as an artificial polyvalent ligand in the investigation of carbohydrate–protein recognition and for the design of site‐specific drug‐delivery systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5754–5765, 2004

show abstract

Section: Methodsmentioning

confidence: 99%

Synthesis and properties of biomimetic poly(L‐glutamate)‐b‐poly(2‐acryloyloxyethyllactoside)‐b‐poly(L‐glutamate) triblock copolymers

Dong

Faucher

Chaikof

2004

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

show abstract

“…N-Boc-protected L-proline (6) was converted quantitatively into the anhydride 7 [7] [15], which was reacted with glycine methyl ester hydrochloride in the presence of Et 3 A C H T U N G T R E N N U N G N, and subsequently exposed to boiling H 2 O to afford the bicyclic diketopiperazine 8 in 87% yield over both steps [16]. Alternatively, compound 8 is accessible in 46% yield according to the method by Viallefont and co-workers [17]. Upon treatment of 8 with Meerweins salt, the desired lactim ether 5 was obtained in 77% yield (67% total yield over four steps).…”

mentioning

confidence: 99%

Diastereoselective Alkylation of a Proline-Derived Bicyclic Lactim Ether

Hendea¹,

Laschat²,

Baro³

et al. 2006

HCA

View full text Add to dashboard Cite

Dedicated to Professor Dieter Hoppe on the occasion of his 65th birthday N-Boc-protected L-proline (6) was converted into the bicyclic lactim ether (8aS)-6,7,8,8a-tetrahydro-1-methoxypyrrolo[1,2-a]pyrazin-4(3H)-one (5) in four steps (Scheme 1). Deprotonation with LDA or LHMDS and subsequent alkylation resulted in the diastereoisomeric products cis-and trans-9. The diastereoselectivity was mainly dependent on the electrophile. Whereas small alkyl halides gave preferably cis-9, sterically more-demanding alkyl halides resulted in cis/trans mixtures. Electrophiles bearing a psystem favored the trans-products 9. Some isolated cis-and trans-lactim ethers 9 were converted to the corresponding diketopiperazines cis-and trans-10 by acid hydrolysis. The structures and configurations of several compounds were confirmed by NMR and NOE experiments, as well as by X-ray crystallography (Figs. 1 -4).Introduction. -In contrast to the well-known Schçllkopf bislactim-ether method for the synthesis of a-amino acids [1 -3], the alkylation of monolactim ethers has been rarely reported in the literature [4 -6]. Recently, we have published the preparation of tricyclic diketopiperazines with an annulated tetrahydroisoquinoline moiety via diastereoselective alkylation of the corresponding monolactim ethers and subsequent hydrolysis [7].Several secondary metabolites of microorganisms with interesting biological properties such as deoxybrevianamide E (1) [8], tryprostatins A and B (2a, b) [9], spirotryprostatin A (3) [10], and fumitremorgin C (4) [11] contain a proline-derived diketopiperazine as part of their molecular skeleton. Furthermore, this type of compound has been found in the bitter flavor of roasted coffee [12]. The diketopiperazine structural motif in these natural products was prepared in most cases by cyclocondensation [8 -11] [13] [14]. However, we were interested to synthesize related proline-based diketopiperazines via alkylation of the bicyclic lactim ether 5, followed by acidic hydrolysis. The results of our investigation are reported in this paper.

show abstract

“…11 The NCA of N -trityl asparagine ( 2 ) was obtained in quantitative yield as white crystals by treatment of commercial N -Boc- N -β-trityl-Asn with PBr 3 . 12 This NCA was heated with the peptide in NMP/THF at 60 °C for 24 h to produce 3 . These stringent conditions show the very low tendency of this NCA to undergo ring-opening polymerization in organic solvents.…”

Section: Resultsmentioning

confidence: 99%