Transannular reactions of cycloalkenes, cycloalkadienes and cycloalkatrienes. 16. Photocyclization of cyclononene and cycloundecene
摘要:
Irradiation of cyclononene (7b) and cycloundecene (7d) in pentane afforded cis-bicyclo[4.3.0]nonane (10b) and cis-bicyclo[6.3.0]undecane (10d), respectively. Small amounts of the fragmentation products 1-undecene (14d) and 1-undecyne (15d) were also obtained from cycloundecene (7d). The photobehavior of the series of medium- and large-ring alkenes 7a-e is compared. Aside from E reversible Z isomerization, the principal pathway in each case involves rearrangement of the pi,R(3s) excited state to the cycloalkylidene intermediate 8, which undergoes predominant, if not exclusive, 1,5-transannular insertion to afford the corresponding cis-bicyclo[n.3.0]alkane (10). The cycloalkylidenes 8 formed in this way exhibit behavior somewhat different from those generated by other methods. The possible contributory role of carbene intermediates derived from pi,R(3s) excited states in E revesible Z photoisomerization of acyclic alkenes is also discussed.
Total Synthesis of Guanacastepene A: A Route to Enantiomeric Control
作者:Mihirbaran Mandal、Heedong Yun、Gregory B. Dudley、Songnian Lin、Derek S. Tan、Samuel J. Danishefsky
DOI:10.1021/jo051470k
日期:2005.12.1
ketone (see compound 41). Actually, cyclization was best accomplished when the terminal double bond of 41 was first converted to an epoxide. Further issues related to the stereochemistry at C5 and, rather surprisingly, the propensity for β-face acetoxylation at C13. Crystallographic verification of the assigned β-stereochemistry at C13 is provided. Finally, a route to opticallyactive material is provided
A New Method for the Preparation of Michael Adducts and Cyclic Enones Using Lithium Chloride-Hexamethylphosphoramide System.
作者:Yutaka OZAKI、Ayako KUBO、Kyouko OKAMURA、Sang-Won KIM
DOI:10.1248/cpb.43.734
日期:——
A new procedure using lithium chloride in hexamethylphosphoramide was found to be useful for the synthesis of Michael-type adducts and cyclic enones. Selectivity for the two products could be controlled by altering the reaction temperature employed. The urea-type solvents were also examined instead of hexamethylphosphoramide.
Zur Kenntnis des Kohlenstoffringes. 51. Mitteilung. Weitere Untersuchungen über die Gültigkeitsgrenzen der<i>Bredt</i>'schen Regel. Eine Variante der<i>Robinson</i>'schen Synthese von cyclischen ungesättigten Ketonen
作者:V. Prelog、P. Barman、M. Zimmermann
DOI:10.1002/hlca.19490320418
日期:——
3-Dichlor-buten-(2)] mit Natrium-cyclanon-(2)-carbonsäure-(1)-estern erhaltenen Verbindungen IV gehen durch Behandlung mit konz. Schwefelsäure in ungesättigte β-Keto-carbonsäureester über, welche je nach der Ringgrösse des Ausgangsmaterials die Konstitution VIIIa (n = 6, 7) oder VIIa (n = 8, 13) besitzen.
1. Die durch Umsetzung vonγ-氯-巴豆酰氯[1,3-Dichlor-buten-(2)] mit Natrium-cyclanon-(2)-carbonsäure-(1)-esterer erhaltenen Verbindungen IV gehen durch Behandlung mit konz 。Schwefelsäure在β-Keto-carbonsäureesterüber的研究中,被任命为VIIIa级(n = 6,7)或VIIa级(n = 8,13)。
The total synthesis of (±)-bulnesol and related studies
作者:J.A. Marshall、J.J. Partridge
DOI:10.1016/s0040-4020(01)82767-8
日期:1969.1
1,7-dimethylbicyclo[4.3.1]decan-10-ols 16e, 19e, and 79 and the subsequent rearrangement of their methanesulfonate derivatives to the corresponding hydroazulenes 22, 27, and 81 is described. The synthesis of the bicyclo[4.3.1]decane intermediates begins with 2-carbethoxycycloheptanones and proceeds via condensation with methyl vinyl ketone and cyclization of the resulting 2-carbethoxy-2-(3-oxobutyl)-cycloheptanones
A Method for the Cyclic Enone Synthesis Using Lithium Chloride – Hexamethylphosphoramide System
作者:Yutaka Ozaki、Ayako Kubo、Sang-Won Kim
DOI:10.1246/cl.1993.993
日期:1993.6
Cyclic enones were obtained from the reactions of β-keto esters with acyclic α,β-unsaturated ketones by using lithium chloride in hexamethylphosphoramide. The products were brought about via the Michael addition, decarboxylation, and the aldol condensation.