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Thermal Ring Contraction of a 1,4-Diazepine. Part II; 6-Chloro-4-phenyl-2-quinazoline carboxaldehyde

SyntheticPage 576
DOI: 10.1039/SP576
Submitted Nov 17, 2012, published Dec 20, 2012
Ramesha Ramakrishna (ramesha63@hotmail.com)
A contribution from ramesha
Reaction Scheme: <img src="/images/empty.gif" alt="" />Thermal Ring Contraction of a 1,4-Diazepine. Part II

Chemicals Used

Oxazepam, 99.5% as per BP
Mix xylene, commercial

Procedure

Oxazepam (10 g, 34.87 mmol) was added to xylene (50 mL) in a 250 mL Dean-Stark apparatus under nitrogen atmosphere. Reaction mixture was refluxed and the progress of the reaction was monitored by TLC. After 24 h, the reaction mixture was cooled to 5-8 oC and the white crystals thus obtained was filtered and dried under vacuum for 6 h at 70-75 oC to get 6-Chloro-4-phenyl-2-quinazoline carboxaldehyde as white crystalline product (8.9 g, 96 %) which is practically pure and does not require further purification.

Author's Comments

1. This reaction is similar to SP544 except that Oxazepam requires higher temperature (xylene reflux) where as Lorazepam rearrangement occours in toluene.
2. This is a clean procedure for the synthesis of - 6-Chloro-4-phenyl-2-quinazoline carboxaldehyde. Other than xylene no other reagent is used in the reaction.

Data

mp: 193-194 oC, IR (KBr); 1722, 1481, 854, 817 cm-1,1H (300 MHz, CDCl3): δ 10.31 (s,1H), 8.28(d, J = 6.7 Hz, 1H), 8.20(d, J=1.29, 1H), 7.96 (dd, J = 6.7,1.5 Hz 1H), 7.83-7.62 (m, 2H), 7.63-7.60 (m, 3H), 13 C (75 MHz, CDCl3) : δ 191.6, 169.1, 155.2, 149.7,136.3, 135.9, 135.7, 131.8, 130.8, 130.0, 128.9, 126.1, 124.0, HRESI-MS (m/z): M+ + Na, found 291.0302. C15H9ClN2ONa requires 291.0301.

Lead Reference

Maravanahalli S. Siddegowda, Hemmige S. Yathirajan, Ramesha A. Ramakrishna. Indian Journal of Chemistry, Vol 51B, 2012, 1628-1632.

Supplementary Information

Spectra for product as images (Oxazepam rearrangement data files.docx)

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Get structure file (.cdx, .sk2, .mol)

Keywords: aldehydes, amides, aromatics/arenes, dehydration, elimination, Oxazepam, quinazoline aldehyde, rearrangement, thermal, xylene