Carbene dimerization

Carbene dimerization is a type of organic reaction in which two carbene or carbenoid precursors react in a formal dimerization to an alkene. This reaction is often considered an unwanted side-reaction but it is also investigated as a synthetic tool. In this reaction type either the two carbenic intermediates react or a carbenic intermediate reacts with a carbene precursor.^[1] An early pioneer was Christoph Grundmann reporting on a carbene dimerisation in 1938.^[2] In the domain of persistent carbenes the Wanzlick equilibrium describes an equilibrium between a carbene and its alkene.

A reoccurring substrate is a diazo compound and more specifically an alpha-carbonyl diazo compound. For example, ethyl diazoacetate is converted to diethyl maleate using the ruthenium catalyst chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium:^[3]

Grubbs' catalyst is also effective ^[4] In this reaction type the active intermediate is a transition metal carbene complex. A diazo cross-coupling reaction has also been reported between ethyl diazoacetate and methyl phenyldiazoacetate using the rhodium catalyst [Rh₂(OPiv)₄].^[5]

A direct metal carbene dimerization has been used in the synthesis of novel Polyalkynylethenes ^[6]

References

↑March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN 9780471854722. OCLC 642506595.
↑Grundmann, C. (1938), Über die Zersetzung der Diazoketone. Justus Liebigs Annalen der Chemie, 536: 29–36.doi:10.1002/jlac.19385360103
↑Highly stereoselective formation of cis-enediones from α-diazo carbonyl compounds catalysed by [RuCl(η5-C5H5)(PPh3)2] Walter Baratta and Alessandro Del Zotto Chem. Commun., 1997, 2163-2164 doi:10.1039/A706459D
↑グラブス第2世代ルテニウムカルベン触媒を用いたアルケニルジアゾ酢酸エステルのヘッドツーヘッド二量化によるジアゾ酢酸エステルからのマレイン酸エステルおよびジラクトンの合成David M. Hodgson および Deepshikha Angrish Chem. Commun., 2005, 4902-4904 doi : 10.1039/B510829B
↑ Hansen, Jørn H.; Parr, Brendan T.; Pelphrey, Philip; Jin, Quihui; Autschbach, Jochen; Davies, Huw ML (2011). "ジアゾ化合物のロジウム(II)触媒によるクロスカップリング". Angewandte Chemie International Edition . 50 (11): 2544– 2548. doi : 10.1002/anie.201004923 .
↑ Barluenga, J.、de Sáa, D.、Gómez, A.、Ballesteros, A.、Santamaría, J.、de Prado, A.、Tomas, M. および Suárez-Sobrino, A. (2008)、金属カルベン二量化: ポリアルキニルエテンへの多彩なアプローチ。アンゲヴァンテ・ケミー国際版、47: 6225–6228。土井：10.1002/anie.200801584

[1] March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN 9780471854722. OCLC 642506595.

[2] Grundmann, C. (1938), Über die Zersetzung der Diazoketone. Justus Liebigs Annalen der Chemie, 536: 29–36.doi:10.1002/jlac.19385360103

[3] Highly stereoselective formation of cis-enediones from α-diazo carbonyl compounds catalysed by [RuCl(η5-C5H5)(PPh3)2] Walter Baratta and Alessandro Del Zotto Chem. Commun., 1997, 2163-2164 doi:10.1039/A706459D

[4] グラブス第2世代ルテニウムカルベン触媒を用いたアルケニルジアゾ酢酸エステルのヘッドツーヘッド二量化によるジアゾ酢酸エステルからのマレイン酸エステルおよびジラクトンの合成David M. Hodgson および Deepshikha Angrish Chem. Commun., 2005, 4902-4904 doi : 10.1039/B510829B

[5] Hansen, Jørn H.; Parr, Brendan T.; Pelphrey, Philip; Jin, Quihui; Autschbach, Jochen; Davies, Huw ML (2011). "ジアゾ化合物のロジウム(II)触媒によるクロスカップリング". Angewandte Chemie International Edition . 50 (11): 2544– 2548. doi : 10.1002/anie.201004923 .

[6] Barluenga, J.、de Sáa, D.、Gómez, A.、Ballesteros, A.、Santamaría, J.、de Prado, A.、Tomas, M. および Suárez-Sobrino, A. (2008)、金属カルベン二量化: ポリアルキニルエテンへの多彩なアプローチ。アンゲヴァンテ・ケミー国際版、47: 6225–6228。土井：10.1002/anie.200801584

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