A New Photochemical Route to Cyclopropanes

Wessig, Pablo; Mühling, Olaf

doi:10.1002/1521-3773(20010316)40:6<1064::aid-anie10640>3.0.co;2-5

Cited by 48 publications

(39 citation statements)

References 14 publications

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“…As depicted in Scheme 53 [74], diastereoselective photochemical cyclization of 192 lead to the product 193. As depicted in Scheme 53 [74], diastereoselective photochemical cyclization of 192 lead to the product 193.…”

Section: Kulinkovich Reactionmentioning

confidence: 99%

Stereoselective Synthesis of Cyclopropanols

Garcı́a¹,

Díez²,

Antón³

et al. 2006

MROC

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Section: Kulinkovich Reactionmentioning

confidence: 99%

Stereoselective Synthesis of Cyclopropanols

Garcı́a¹,

Díez²,

Antón³

et al. 2006

MROC

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“…A great deal of research has been focused on development new and wide-ranging methods to synthesize cyclopropanated products [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The Norrish-Yang reaction was demonstrated to be useful to synthesize cyclopropane products for some molecules [18]. These are only a few examples of the diverse range of methods that have been used for cyclopropanation reactions.…”

Section: Introductionmentioning

confidence: 99%

“…Since the reported use of diiodomethane and a Zn/Cu couple to react with olefins to form cyclopropane units by Simmons and Smith, the cyclopropanation reaction were catalyzed by transition metals to form active reagents similar to the SimmonsSmith reagent that can make cyclopropane-containing products from olefins with high efficiency and stereoselectivity. To our best knowledge, many transition metals such as Rh, Ru, Pd, Pt, Ni, Cu, Zn, Sm, Al and Li are found to be able to catalyze cyclopropanation via a metal-carbene complex [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Zhao and co-workers have studied the reaction mechanism of samarium (II) carbenoid promoted cyclopropanation reaction with ethylene and the effect of THF solvent [34].…”

Section: Introductionmentioning

confidence: 99%

A DFT Study on the Mechanism of Samarium (II)-catalyzed Cyclopropanation Synthesis with α,β -unsaturated Carboxylic Acids, Alcohols and Amides

Zhang¹,

Geng²,

Wang³

et al. 2012

COC

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The mechanisms and regioselectivity of samarium(II)-catalyzed cyclopropanation synthesis with , -unsaturated carboxylic acids, alcohols and amides have been investigated using density functional theory calculations at B3LYP/6-31G(d,p) (LANL2DZ for I and RECPs for Sm) level of theory. Solvent effects on these reactions were explored using calculations that included a polarizable continuum model (PCM) for the solvent (THF). Our calculations suggest that the reaction proceeds through two possible channels: methylene transfer and carbometalation. The results show that the activation energies and mechanisms have larger differences, which have been briefly compared with the different , -unsaturated substrates. The reactions for , -unsaturated carboxylic acids both the carbometalation pathway and the methylene transfer pathway are feasible, while the carbometalation channel occurs more easily. For , -unsaturated alcohols, it is widely favored that the methylene transfer mechanism over carbometalation mechanism, while the energy barriers for , -unsaturated amides are relatively higher of 16.4-23.1 kcal/mol. The computational results are in good explanation with the experimental observations of Concellón, et al. on the cyclopropanation reaction of samarium(II)-catalyzed synthesis based on , -unsaturated substrates.

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“…The structures of the a-substituted butyrophenones used in this study (1)(2)(3)(4)(5)(6) are shown here. The photochemistry of these compounds has already been evaluated by us [7,8] and by Wessig et al [12] for the mesylate 5.…”

Section: Introductionmentioning

confidence: 99%

α‐Carbonyl Substituent Effect on the Lifetimes of Triplet 1,4‐Biradicals from Norrish‐Type‐II Reactions

Cai

Cygon²,

Goldfuß³

et al. 2006

Chemistry A European J

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Triplet 1,4-biradicals were generated by Norrish-Type-II hydrogen transfer from alpha-heteroatom-substituted beta-branched butyrophenones 1-6 and detected by laser flash absorption measurements. For three oxy-substituted compounds 2-4 (R(alpha)=OH, OCOMe, OCOOEt) comparable lifetimes were determined in acetonitrile (roughly 1.5 micros). In benzene, divergent trends were observed: for the hydroxy compound 2 a lower lifetime of 790 ns was determined, whereas for 3 and 4 the lifetimes increased to 4.9 micros. Photolyses of the alpha-amino-substituted compounds 1 and 6 resulted in transient species with significant lower lifetimes (for 1 160 ns in benzene and 450 ns in acetonitrile; for 6 <100 ns in both solvents). The mesyloxy substrate 5 undergoes rapid C-O bond cleavage upon photolysis and no transient triplet species were detected. Computational (UB3 LYP/6-31G* and natural don orbital (NBO) analyses) results supported the assumption of a negative hyperconjugative interaction strongly stabilizing alpha-oxy-substituted over alpha-amino-substituted radicals.

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A New Photochemical Route to Cyclopropanes

Cited by 48 publications

References 14 publications

Stereoselective Synthesis of Cyclopropanols

Stereoselective Synthesis of Cyclopropanols

A DFT Study on the Mechanism of Samarium (II)-catalyzed Cyclopropanation Synthesis with α,β -unsaturated Carboxylic Acids, Alcohols and Amides

α‐Carbonyl Substituent Effect on the Lifetimes of Triplet 1,4‐Biradicals from Norrish‐Type‐II Reactions

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A New Photochemical Route to Cyclopropanes

Cited by 48 publications

References 14 publications

Stereoselective Synthesis of Cyclopropanols

Stereoselective Synthesis of Cyclopropanols

A DFT Study on the Mechanism of Samarium (II)-catalyzed Cyclopropanation Synthesis with &#945;,&#946; -unsaturated Carboxylic Acids, Alcohols and Amides

α‐Carbonyl Substituent Effect on the Lifetimes of Triplet 1,4‐Biradicals from Norrish‐Type‐II Reactions

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A DFT Study on the Mechanism of Samarium (II)-catalyzed Cyclopropanation Synthesis with α,β -unsaturated Carboxylic Acids, Alcohols and Amides