Synthesis of Benzoxazines, 3,4-Dihydroquinazolines and Quinazolinethiones

2-Anilino-5-benzoyl-4-phenyl-1,3-thiazole

“…For general background, see: Dridi et al (1998);El Efrit et al (1996); Gorczynski et al (2004); Wipf et al (2001). For structural information, see: Allen (2002); Etter et al (1990); Bernstein et al (1995).…”

“…. As a part of our ongoing research focused on the use of N-functionalized imidates in heterocyclic syntheses (El Efrit et al, 1996, Dridi et al, 1998, we show that, in presence of sodium hydride (NaH), the reaction of N-thiocarbamoylimidate, Ph-C(OMe)=N-C(NHPh)=S, with 2-Bromo-1-phenylethanone (Br-CH2-C(O)-Ph) can can theoretically lead to thiazole or diazole isomeric ring.…”

One-Pot Tandem Assembly of Amides, Amines, and Ketones: Synthesis of C4-Quaternary 3,4- and 1,4-Dihydroquinazolines

“… The reaction involved in situ generation of imines from aldehydes and amines, after which the imine became incorporated into the heterocyclic scaffold, with the starting aldehyde’s carbon bulk making up the newly formed DHQ C4 carbon and its attached substituent (e.g., R 4 ). Whereas the use of imines in the reaction afforded compounds with tertiary C4 centers, an analogous reaction involving the installation of ketimines would instead give rise to C4-quaternary 3,4-DHQs. Challenges for such a reaction were envisioned to mirror those of traditional Pictet–Spengler methods of quaternary center formation, namely difficulty in both the formation of ketiminium reaction intermediates and in cyclization to generate the new heterocyclic rings due to enhanced steric bulk and reduced electrophilicity of ketimines relative to imines .…”

“…14 The reaction involved in situ generation of imines from aldehydes and amines, after which the imine became incorporated into the heterocyclic scaffold, with the starting aldehyde's carbon bulk making up the newly formed DHQ C4 carbon and its attached substituent (e.g., R 4 ). Whereas the use of imines in the reaction afforded compounds with tertiary C4 centers, an analogous reaction involving the installation of ketimines 15 would instead give rise to C4-quaternary 3,4-DHQs.…”