478659-48-2

Upstream product

• 13734-34-4 N-tert-butoxycarbonyl-L-phenylalanine 
• 478659-08-4 (+)-methyl N'-(t-butyloxycarbonyl)-L-phenylalanyl-N-methylglycinate 
• 478659-17-5 (+)-(3S)-3-benzyl-5-ethoxy-1-methyl-3,6-dihydro-1H-2-pyrazinone 
• 59017-01-5 (-)-(3S)-3-benzyl-1-methyl-2,5-piperazinedione 
• 478659-23-3 (+)-(4S)-4-benzyl-2-methyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-dione 

Downstream Products

• 478659-51-7 (+)-(1R,4S)-4-benzyl-1-hydroxy-2-methyl-1-phenyl-2,4-dihydro-(1H)-pyrazino[2,1-b]quinazoline-3,6-dione 

Relevant academic research and scientific papers

Acid-promoted reactions in 1-hydroxy, 1-dimethylaminomethyl and 1-methylene-4-arylmethyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones

The 1-dimethylaminomethyl or 1-methylene group of the title compounds was introduced through a Mannich or a tandem of Mannich-Hofmann reactions as the final step of a protocol that is shorter than other previously described for these precursors of N-acyliminium species. In these compounds, the acid-promoted intramolecular cyclizations of Pictet-Spengler-type were restricted to the N(2)-unsubstituted compounds, while their N(2)-methyl substituted analogues gave instead dimerization products. The cyclization was effective with 1-hydroxy-1,2-disubstituted compounds, which were obtained through addition of a Grignard reagent to 2H,4H-pyrazino[2,1-b]quinazoline-1,3,6-triones.