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Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion

Record Type:	Electronic resources : Monograph/item
Title/Author:	Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion
Author:	Sogi, Miki.
Description:	172 p.
Notes:	Adviser: Andrew G. Myers.
Notes:	Source: Dissertation Abstracts International, Volume: 65-01, Section: B, page: 0228.
Contained By:	Dissertation Abstracts International65-01B.
Subject:	Chemistry, Organic.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3118006
ISBN:	0496654306

Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion
Sogi, Miki.

Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion [electronic resource] - 172 p.

Adviser: Andrew G. Myers.

Thesis (Ph.D.)--Harvard University, 2004.

Investigations of potential synthetic pathways to 1 initially utilized as starting material the tricyclic carbonate 11, the product of an intramolecular [2+2] photocyclization reaction. In these studies, 11 was transformed in several steps to the distannane 12, which upon treatment with boron fluoride ethyl etherate is believed to have formed the unstable hydrocarbon bicyclopentadienylidene (13). In an effort to avoid cleavage of the central, 4-membered ring of unsaturated tricyclo[5.3.0.02,6]decane intermediates (perhaps the result of 10-electron electrocyclic ring-opening of the tetraene 8), synthetic approaches to 1 employing cobalt-cyclobutadiene complexes 18 and 19 were pursued. However, treatment of 18 with excess methyllithium led to the novel cobaltacyclic product 30, and dehydration of 19 in the presence of pyridine produced the ring-opening cobaltacyclic product 35. It is proposed that both processes may occur by a 10-electron electrocyclic ring-opening reaction of eta2-organocobalt intermediates. These processes may be related to the hypothetical transformation of tetraene 8 to bicyclopentadienylidene (13).

ISBN: 0496654306Subjects--Topical Terms:

193634
Chemistry, Organic.

Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion
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245 1 0 $a Synthetic and theoretical studies of cyclobuta[1,2:3,4]dicyclopentene. Organocobalt intermediates in the construction of the unsaturated carbon skeleton and their transformation into novel cobaltacyclic complexes by C-C insertion $h [electronic resource]
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502 $a Thesis (Ph.D.)--Harvard University, 2004.
520 # $a Investigations of potential synthetic pathways to 1 initially utilized as starting material the tricyclic carbonate 11, the product of an intramolecular [2+2] photocyclization reaction. In these studies, 11 was transformed in several steps to the distannane 12, which upon treatment with boron fluoride ethyl etherate is believed to have formed the unstable hydrocarbon bicyclopentadienylidene (13). In an effort to avoid cleavage of the central, 4-membered ring of unsaturated tricyclo[5.3.0.02,6]decane intermediates (perhaps the result of 10-electron electrocyclic ring-opening of the tetraene 8), synthetic approaches to 1 employing cobalt-cyclobutadiene complexes 18 and 19 were pursued. However, treatment of 18 with excess methyllithium led to the novel cobaltacyclic product 30, and dehydration of 19 in the presence of pyridine produced the ring-opening cobaltacyclic product 35. It is proposed that both processes may occur by a 10-electron electrocyclic ring-opening reaction of eta2-organocobalt intermediates. These processes may be related to the hypothetical transformation of tetraene 8 to bicyclopentadienylidene (13).
520 # $a This thesis describes theoretical and synthetic studies of the tricyclic 10pi electron hydrocarbon cyclobuta[1,2:3,4]dicyclopentene (1), a nominally aromatic structure that has never been synthesized. Geometry optimization by density-functional-theory calculations (B3LYP/6-31G(d,p)) predict that 1 is a D2h symmetric structure with non-alternant C--C single- and double-bonds. The calculations also predict that 1 is 4.7 kcal/mol higher in energy than the isomeric hydrocarbon 1,6-didehydro[10]annulene (2), a molecule known to isomerize to 1,5-didehydronaphthalene (4) above -50°C. Calculated enthalpic changes of homodesmotic reactions support the notion that 1 is an aromatic molecule with a resonance stabilization energy (RSE) about half to two-thirds that of benzene on per-molecule basis.
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