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A lactam is a cyclic amide. The term is a portmanteau of the words ''lactone'' + ''amide''. ==Nomenclature== Greek prefixes in alphabetical order indicate ring size: * α-Lactam (3 ring atoms) * β-Lactam (4 ring atoms) * γ-Lactam (5 ring atoms) * δ-Lactam (6 ring atoms) * ε-Lactam (7 ring atoms) This ring-size nomenclature stems from the fact that a hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, ''etc''. ==Synthesis== General synthetic methods exist for the organic synthesis of lactams. * Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. * Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction. * Lactams form from cyclisation of amino acids. * Lactams form from intramolecular attack of linear acyl derivatives from the nucleophilic abstraction reaction. * In iodolactamization 〔Spencer Knapp, Frank S. Gibson Organic Syntheses, Coll. Vol. 9, p.516 (1998); Vol. 70, p.101 (1992) (Online article )〕 an iminium ion reacts with an halonium ion formed in situ by reaction of an alkene with iodine. : * Lactams form by copper-catalyzed 1,3-dipolar cycloaddition of alkynes and nitrones in the Kinugasa reaction * Diels-Alder reaction between cyclopentadiene and chlorosulfonyl isocyanate (CSI) can be utilized to obtain both β- as well as γ-lactam. At lower temp (−78°C), β-lactam is the preferred product. At optimum temperatures, a highly useful γ-lactam known as Vince Lactam〔Singh, R.; Vince, R. ''Chem. Rev.'' 2012, ''112 (8),'' pp 4642–4686."2-Azabicyclo()hept-5-en-3-one: Chemical Profile of a Versatile Synthetic Building Block and its Impact on the Development of Therapeutics"〕 is obtained.〔Pham, P.-T.; Vince, R. ''Phosphorus, Sulphur and Silicon'' 2007, 779-791. 〕 Preparation of VL and beta lactam 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「lactam」の詳細全文を読む スポンサード リンク
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