Producción Científica Profesorado

Synthesis of New Chiral Derivatives of N,N?-Dimethylpropyleneurea (DMPU) and Examination of Their Influence on the Regio- and Enantioselectivity of Addition of 2-(1,3-Dithianyl)lithium to Cyclohex-2-en-1-one



Lopez Ruíz, Heraclio

2002

E. Juaristi, M. Hernandez-Rodriguez, Heraclio López-Ruiz, J. Aviña, O. Muños-Muniz, M. Hayakawa, D. Seebach. Synthesis of New Chiral Derivatives of N,N-Dimethylpropyleneurea (DMPU) and Examination of Their Influence of the Regio- and Enentioselective of Addition of 2(1,3Dithianyl)lithium to Cyclohex-2-en-one. Helvetica Chimica Acta, 85, 1999-2007 (2002). DOI: 10.1002/1522-2675(200207)85:7<1999::AID-HLCA1999>3.0.CO;2-K


Abstract


The preparation of three new chiral derivatives of DMPU (N,N?-dimethylpropyleneurea) is described (Schemes?24); one type of derivative carries 1-phenylethyl or 1-cyclohexylethyl groups at the N-atoms of the tetrahydropyrimidin-2(1H)-one ring (2 and 4), another type of derivative is substituted at C(4) and C(6) of the heterocyclic ring (7). The potential of these chiral Lewis bases as promoters in the regio- and/or enantioselective addition of 2-(1,3-dithianyl)lithium to cyclohex-2-en-1-one was explored; they are all unable to effect enantioselective addition; the derivatives with branched substituents at the N-atoms do not shift the addition mode from 1,2 to 1,4, while the 3,4,5,6-tetrahydro-1,3,4,6-tetramethylpyrimidin-2(1H)-one does (Scheme?5). The results provide useful information regarding the nature of the nucleophilic organolithium reagent: obviously, the steric hindrance to Li complexation on the CO O-atom of the tetrahydropyrimidin-2(1H)-one by branched substituents at N-atoms (cf. X-ray crystal structure of 2 in the Fig.) prevents solvent-separated-ion-pair (SSIP) formation; this was confirmed by PM3 and B3LYP/3-21-G(d)//PM3 calculations (Scheme?6).



Producto de Investigación




Artículos relacionados

Synthesis and Structures of some Lithium and Sodium (Aminoalcoholato)hydrido Aluminates

Phenylboronic acid catalyzed-cyanide promoted, one-pot synthesis of 2-(2-hydroxyphenyl)benzoxazole d...

Addition reaction of benzylbenzylidenenamine to lithium enolates of 1,3-dioxolan-4-one: synthesis of...

Stereoselective addition of allylmagnesium chloride to the CN bond of [4.3.0] boron heterobicycles

Preparation of Seven- and Eight-Membered Boron Heterocycles from Different Salen Ligands and Arylbor...

Study of the reactivity of squarylferrocenes. Addition of amines and aminoesters

An efficient potassium cyanide-promoted synthesis of 2-arylbenzoxazoles from [4.3.0]boron heterobicy...

Synthesis and Study of Monomeric and Dimeric Boronates by Spectroscopic Methods and X-ray Crystallog...

Structure-Activity Relationships for Inhibition of Cysteine Protease Activity and Development of Pla...

Synthesis of nitrogen-, oxygen- and sulphur-containing tripodal ligands with a trimethylbenzene core...