The synthesis of multisubstituted
1-aminoindanes through catalyst-controlled
diastereodivergent [3 + 2] annulation of aromatic imines with alkenes
is of great interest and importance. An understanding of the exact
reaction mechanism, especially for the origin of diastereoselectivity,
is an essential aspect for further development of such reactions.
In this study, density functional theory calculations have been carried
out on the rare-earth-catalyzed diastereodivergent [3 + 2] annulation
of benzaldimine with styrene. The results show that the reaction mainly
involves generation of active species, olefin insertion, cyclization,
and protonation steps. The noncovalent interactions, such as C–H···π
and metal···π interactions, play an important
role in stabilizing the key transition state or intermediate. Both
steric and electronic factors account for the diastereoselectivity.
The preferred cis-diastereoselectivity could be ascribed
to more efficient orbital interaction, while the crowded space will
induce the formation of a C–H···π interaction
between the N
t
Bu group and benzene ring
in a trans-diastereoselectivity manner, thus stabilizing
the trans-selective transition state. Therefore,
the stereospecific product could be obtained by fine-tuning the ligand/metal
combination of the catalysts.
Molecular-level understanding of metal-mediated white phosphorus (P 4)a ctivation is meaningful but challenging because of its direct relevance to the conversion of P 4 into useful organophosphorus compounds as well as the complicateda nd unforeseeable cleavage process of PÀP bonds. The related study,h owever,h as still rarely been achieved to date. Here, at heoretical insighti nto the stepby-step process of three PÀPb ond cleavage/four PÀCb ond formation for [P 3 + +P 1 ]-fragmentation of P 4 mediated by lutetacyclopentadienes is reported. The unique charge-separated intermediate and the intermolecular cooperation between two lutetacyclopentadienes play av ital role in the subsequentP ÀP/PÀCb ondb reaking/forming. It is found that, although the first PÀCf ormation is involved in the assembly of the cyclo-P 3 [R 4 C 4 P 3 ] À unit, the construction of the aromatic five-membered P 1 heterocycle [R 4 C 4 P] À is completed prior to the cyclo-P 3 formation. The reaction mechanism has been carefully elucidated by analyses of the geometric structure, frontier molecular orbitals, bond index,and natural charge, which greatly broaden and enrich the general knowledge of the direct functionalization of P 4 .
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