Dichlorocarbene Addition to Cyclopropenes:  A Computational Study

Merrer, Dina C.; Rablen, Paul R.

doi:10.1021/jo048161z

Cited by 28 publications

(59 citation statements)

References 44 publications

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“…Summing the trajectories that either terminate as or proceed through 2a , the ratio of bicyclobutane‐mediated trajectories to butadiene‐forming trajectories (i.e., Brinker's product ratio: ( 2a + 4a )/ 5a ) is 323/69 = 4.7. Therefore, molecular dynamics has successfully modeled Brinker's experimental product ratio of 4:1, which supports our previous proposal: CCl 2 addition to cyclopropene is controlled by reaction dynamics.…”

Section: Resultssupporting

confidence: 85%

“…Our previous computational study of CCl 2 + cyclopropene ( 1a , and also 1b and R = CH 3 , CH=CH 2 ) showed Brinker's major (bicyclobutane 2a ) and minor (butadiene 5a ) products to derive from the same TS in a concerted manner . Specifically, we did not find a zwitterionic intermediate on the potential energy surface of CCl 2 + cyclopropene, and the paths to form 2a and 5a diverged after the TS .…”

Section: Introductionmentioning

confidence: 51%

“…Trajectories were allowed to run to completion if bicyclobutane 2a or cyclobutene 4a was formed. Closed‐shell B3LYP/6‐31G* was utilized because this level of theory was used in our previous computational study of CCl 2 + cyclopropene …”

Section: Resultsmentioning

confidence: 99%

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Dynamic control of dichlorocarbene addition to cyclopropene

Merrer

Doubleday

2011

J of Physical Organic Chem

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The addition of dichlorocarbene to cyclopropene has been studied with direct dynamics quasiclassical trajectories using B3LYP/6‐31G*. The trajectories yielded 1,1‐dichlorobicyclo[1.1.0]butane and 1,1‐dichloro‐1,3‐butadiene in a ratio of 4.7:1, which is consistent with the experimental ratio of 4:1. The large majority of trajectories formed products within 100 fs of the start of the trajectory and proceeded in a concerted manner to the bicyclobutane or butadiene; no zwitterion or biradical intermediate was observed. Eight trajectories generated bicyclobutane and subsequently dissociated chloride to form an ion pair, which recombined to form 2,3‐dichlorocyclobutene. The lifetime of the ion pair averaged 95 fs, which was too short to be considered an intermediate, consistent with previous calculations that characterized the ion pair as a transition state. This study lends strong support to the previous proposition that the addition of CCl2 to cyclopropene is controlled by dynamic effects. Copyright © 2011 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 51%

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Dynamic control of dichlorocarbene addition to cyclopropene

Merrer

Doubleday

2011

J of Physical Organic Chem

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“…Two-step mechanisms for carbene addition to olefins were discussed previously by Jones and Moss. [4] While the recent computational investigation of Merrer and Rablen [48] does not lend support to the existence of intermediates in the reaction of CCl 2 with cyclopropenes, [49][50][51][52] the rearrangements of vinyl-substituted cyclopropylcarbenes are best rationalized by a diradicaloid intermediate. [53,54] The computational analysis of the ethylene + CF 2 reaction by Bernardi et al [55] at the (4,4)-CASSCF/6-31G* level suggested a two-step mechanism with a diradical intermediate having a barrier to ring closure of only 0.2 kcal mol À1 .…”

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confidence: 99%

Addition of Carbenes to the Sidewalls of Single‐Walled Carbon Nanotubes

Bettinger

2006

Chemistry A European J

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The addition of carbenes CX(2) (X=H, Cl) to single-walled carbon nanotubes (SWNTs) was investigated by density functional theory and finite, hydrogen-terminated nanotube clusters or periodic boundary conditions in conjunction with basis sets of up to polarized triple-zeta quality. For armchair [(3,3) to (12,12)] and zigzag tubes [(3,0) to (18,0)], reaction of CH(2) with the C--C bond oriented along the tube axis (A) is less exothermic than with those C--C bonds having circumferential (C) orientation. This preference decreases monotonically with increasing tube diameter for armchair, but not for zigzag tubes; here, tubes with small band gaps have a very low preference for circumferential addition. Axial addition results in cyclopropane products, while circumferential addition produces "open" structures for both armchair and zigzag tubes. The barriers for addition of dichlorocarbene to a (5,5) SWNT, studied for a finite C(90)H(20) cluster, are higher than that for addition to C(60), in spite of similar diameters of the carbon materials. Whereas addition of CCl(2) to [60]fullerene proceeds in a concerted fashion, addition to a (5,5) armchair SWNT is predicted to occur stepwise and involve a diradicaloid intermediate according to B3LYP, PBE, and GVB-PP computations. Addition to C bonds of (5,5) armchair tubes resulting in the thermodynamically more stable insertion products is kinetically less favorable than that to A bonds yielding cyclopropane derivatives.

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“…We previously showed the formation of butadiene to result from dynamic effects. 25,26 isomerization of 1a to 6a in an Ar matrix. 19 Path E outlines stepwise carbene addition to 6a followed by rearrangement and loss of N 2 , whereas path F is the concerted analogue.…”

Section: ■ Introductionmentioning

confidence: 99%

Experimental and Computational Mechanistic Investigation of Chlorocarbene Additions to Bridgehead Carbene–Anti-Bredt Systems: Noradamantylcarbene–Adamantene and Adamantylcarbene–Homoadamantene

et al. 2015

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Cophotolysis of noradamantyldiazirine with the phenanthride precursor of dichlorocarbene or phenylchlorodiazirine in pentane at room temperature produces noradamantylethylenes in 11% yield with slight diastereoselectivity. Cophotolysis of adamantyldiazirine with phenylchlorodiazirine in pentane at room temperature generates adamantylethylenes in 6% yield with no diastereoselectivity. (1)H NMR showed the reaction of noradamantyldiazirine + phenylchlorodiazirine to be independent of solvent, and the rate of noradamantyldiazirine consumption correlated with the rate of ethylene formation. Laser flash photolysis showed that reaction of phenylchlorocarbene + adamantene was independent of adamantene concentration. The reaction of phenylchlorocarbene + homoadamantene produces the ethylene products with k = 9.6 × 10(5) M(-1) s(-1). Calculations at the UB3LYP/6-31+G(d,p) and UM062X/6-31+G(d,p)//UB3LYP/6-31+G(d,p) levels show the formation of exocyclic ethylenes to proceed (a) on the singlet surface via stepwise addition of phenylchlorocarbene (PhCCl) to bridgehead alkenes adamantene and homoadamantene, respectively, producing an intermediate singlet diradical in each case, or (b) via addition of PhCCl to the diazo analogues of noradamantyl- and adamantyldiazirine. Preliminary direct dynamics calculations on adamantene + PhCCl show a high degree of recrossing (68%), indicative of a flat transition state surface. Overall, 9% of the total trajectories formed noradamantylethylene product, each proceeding via the computed singlet diradical.

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Dichlorocarbene Addition to Cyclopropenes: A Computational Study

Cited by 28 publications

References 44 publications

Dynamic control of dichlorocarbene addition to cyclopropene

Dynamic control of dichlorocarbene addition to cyclopropene

Addition of Carbenes to the Sidewalls of Single‐Walled Carbon Nanotubes

Experimental and Computational Mechanistic Investigation of Chlorocarbene Additions to Bridgehead Carbene–Anti-Bredt Systems: Noradamantylcarbene–Adamantene and Adamantylcarbene–Homoadamantene

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