204513-00-8

Upstream product

• 118-92-3 anthranilic acid 
• 204581-66-8 (3S)-3-methyl-1-(4-methoxybenzyl)piperazine-2,5-dione 
• 60857-16-1 N-(4-methoxybenzyl)glycine ethyl ester 
• 1027735-09-6 [((S)-2-Benzyloxycarbonylamino-propionyl)-(4-methoxy-benzyl)-amino]-acetic acid ethyl ester 
• 700269-21-2 5-ethoxy-1-(4-methoxy-benzyl)-3-methyl-3,6-dihydro-1H-pyrazin-2-one 

Downstream Products

• 204770-77-4 (1S,4S)-2-(4-Methoxy-benzyl)-1,4-dimethyl-1,2-dihydro-2,4a,9-triaza-anthracene-3,10-dione 
• 204581-50-0 (1R,4S)-1-(2,2-Dimethyl-propionyl)-2-(4-methoxy-benzyl)-4-methyl-1,2-dihydro-2,4a,9-triaza-anthracene-3,10-dione 
• 357666-70-7 (1S,4S)-1-ethoxy-4-methyl-2-(4-methoxybenzyl)-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-dione 
• 204770-99-0 (4S)-4-methyl-1,2,3,4-tetrahydro-5H-pyrazino[2,1-b]quinazoline-3,6-dione 

Relevant academic research and scientific papers

Solvent-free cyclocondensation of lactim ethers with anthranilic acid under microwave irradiation

Microwave irradiation greatly improves the results of the cyclocondensation between anthranilic acid and lactim ethers derived from 2,5-piperazinediones in terms of reaction times, yields and stereocenter integrity, leading to pyrazino[2,1-b]quinazoline-3,6-diones. The microwave-assisted reaction was also much better than the thermal one when applied to a bis-lactim ether, leading to the corresponding pentacyclic pyrazino [2,1-b:5,4-b′]diquinazoline-5,13- dione in excellent yield, and it also improved the preparation of compounds containing the ring system of the anti-MDR natural product N-acetylardeemin.

Intramolecular friedel-crafts-type reactions involving N-acyliminium ions derived from glycine templates

Enantiomerically pure 4-substituted 2-aralkyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones (1b-m) in which the alkyl chain is (CH2)n, n = 1-3, behave as glycine templates giving by treatment with [hydroxy(tosyloxy)iodo]benzene in ethyl acetate cis-1-tosyloxy derivatives. When these compounds contain electron-rich aryl substituents with n = 2, they spontaneously cyclize through intramolecular Friedel-Crafts-type diastereoselective reactions to give penta- or hexacyclic compounds. Otherwise, they give by solvolysis cis-1-alkoxy derivatives, which in a second step, may be cyclized in acid if n = 2, 3. All these reactions must occur through N-acyliminium species in SN1-like mechanisms. 1-Alkoxy-2-arylmethyl derivatives are reluctant to cyclize, giving trans-1-hydroxy compounds as the only isolated reaction products.

Stereochemical course of acylation and aldol condensation in (4S)-4-methyl-2-benzyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones

Acylation of 1 leads to the syn derivatives 2. Traces of the anti isomers equilibrate to the syn isomers when stored in CHCl3. Aldol condensation showed great diastereoselectivity, but racemization could not be avoided. The configuration of the