Diastereoselective synthesis of new Thiazolyl-Indazole derivatives from R-carvone: A combined experimental and theoretical study

TETRAHEDRON

卷:78

Article

Ousidi, A. N'Ait¹  Itto, M. Y. Ait¹  Auhmani, A.¹  Loubidi, M.¹  Riahi, A.²  Daran, J-C³  Esseffar, M.¹  Parish, Carol A.⁴ 

[1] Cadi Ayyad Univ, Fac Sci Semlalia, Dept Chim, BP 2390, Marrakech, Morocco

[2] Univ Reims, Inst Chim Mol Reims ICMR, CNRS, UMR UFR Sci 7312, BP 1039, F-51687 Reims 2, France

[3] CNRS, Lab Chim Coordinat, 205 Route Narbonne, F-31077 Toulouse 04, France

[4] Univ Richmond, Gottwald Ctr Sci, Dept Chem, Richmond, VA 23173 USA

关键词: Thiosemicarbazones;    1,3-Thiazole;    Indazole;    Diastereoisomers;    NMR;    X-ray crystal structure;    Density functional theory (DFT);   

DOI  :  10.1016/j.tet.2020.131830

来源: Elsevier

【 摘 要 】

The reaction of (R)-carvone and (R)-pulegone thiosemicarbazones with phenacyl bromide yields two new thiazoles: (R)-2-(2-(5-isopropyl-2-methylcyclohex-2-enylidene) hydrazinyl)-4-phenylthiazole, I and (3aR,6R)-3,3,6-trimethyl-2-(4-phenylthiazol-2-yl)-3,3a,4,5,6,7-hexahydro-2H-indazol-3a-ol, II, respectively. While HRMS and NMR spectroscopic data confirm the expected structure of I, they show that the product from (R)-pulegone undergoes rearrangement and oxidation to give II. The orientation of the OH group in II produces two possible diastereoisomers; (3aR,6R) and (3aS,6R). X-Ray analysis was used to assign the (3aR,6R) configuration to II. Energetic analysis with the M052-X functional with 6-31+G(d,p) basis set showed that the (3aR,6R) is more stable than the (3aS,6R) diatereoisomer by approximately 4.5 kcal/mol. The dimerization of the (3aR,6R) isomer of II was studied computationally via two types of hydrogen bonding interactions: (OH center dot center dot center dot O), as the conventional hydrogen bonding, and the interaction of the OH group with the aromatic ring (OH center dot center dot center dot Ar). We find that these two modes of polymerization are approximately isoenergetic. (C) 2020 Elsevier Ltd. All rights reserved.

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