Iranian Journal of Organic Chemistry Vol. 2, No. 1 (2010) 290-296
S. M. Habibi-Khorassani et al.
Quantum mechanical calculation for determination of more stable isomer of
phosphorous ylide involving an indole
Sayyed Mostafa Habibi-Khorassani,
* Ali Ebrahimi,
Malek Taher Maghsoodlou,
, Majid Moradian
Department of Chemistry, University of Sistan and Baluchestan, P. O. Box 98135-674, Zahedan, Iran
Department of Chemistry, Islamic Azad University of Ghaemshahr, Ghaemshahr, Iran
Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reactions between
triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of NH-acid, such as indole. These stable ylides exist in
solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond
resulting from conjugation of the ylide moiety with the adjacent carbonyl group.
In the recent work, the stability of the
- isomers were undertaken for the two rotamers of phosphorus ylides involving an indole [namely dimethyl 2-(indole-1-
yl)-3-(triphenyl- phosphanylidene)- butanedioate(
)] by means of atoms in molecules AIM, CHelpG and NBORead methods.
Stable phosphorus ylides; Dialkyl acetylenedicarboxylates;
rotamer; AIM method.
Phosphorus ylides are important reagents in synthetic
naturally occurring compounds with biological and
phosphorus ylides is an important reaction in organic
compounds in the synthesis of organic products
treatment of a phosphonium salt with a base. Most of
the phosphonium salts are usually made from the
reaction of phosphine and an alkyl halide [4-8], though
phosphorus nucleophiles to activated olefins [3,4]. A
, dialkyl acetylendicarboxylates
(as a NH-acid) has been earlier reported
. The reaction is shown in Fig 1. The
isomers were optimized for all ylide structures at HF/6-
31G(d,p) level of theory by Gaussian 98 package
program. The energy of both geometrical isomers have
been calculated at B3LYP/6-311++G** level. Atoms
in molecules AIM, CHelpG and NBORead methods at
HF/6-31G(d,p) level of theory have been performed in
of phosphorus ylides.
The numbers of critical points and intramolecular