Photolysis of dipropyldiazirine and trapping of dipropylcarbene with piperidine
作者:Eunju Lee Tae、Matthew S Platz
DOI:10.1016/s0040-4039(99)00356-1
日期:1999.4
pathway involves dipropylcarbene formed directly from the diazirine, the other pathways are attributed to ionic and photochemical reactions of 4-diazoheptane and to the excited state of the diazirineprecursor. Dipropylcarbene can be easily intercepted with a simple trap. The yield of this process is limited by the efficiency with which the precursor forms the carbene.
Chemistry and Kinetics of Dipropylcarbene in Solution
作者:Eunju Lee Tae、Zhendong Zhu、Matthew S. Platz、John Paul Pezacki、John Warkentin
DOI:10.1021/jp990198d
日期:1999.7.1
The photochemistry of 2-methoxy-2-methyl-5,5-dipropyl-Delta(3)-1,3,4-oxadiazoline (1a) and 2,2-dimethoxy-5,5-dipropyl-Delta(3)-1,3,4-oxadiazoline (1b) was investigated. Photolysis (300 nm) of these compounds in solution leads to fragmentation to 4-diazoheptane (major), which slowly forms the corresponding azine. Fragmentation to form 4-heptanone is also observed. Yields of 4-diazoheptane in CH2Cl2 are much larger than those in pentane. 4-Diazoheptane can be trapped with 1-pentene to form a pyrazoline or with methanol to form 4-methoxyheptane. The pyrazoline can be decomposed photochemically to form 1,1,2-tripropylcyclopropane. In solution, 4-diazoheptane is inefficiently photolyzed to dipropylcarbene (DPC), which can be trapped with piperidine or with pyridine in laser flash photolysis experiments. Analysis of the piperidine and pyridine data indicates that the lifetime of DPC in cyclohexane, methylene chloride, or Freon-113 (CF2ClCFCl2) solution at ambient temperature is controlled by 1,2 hydrogen migration to form Z- and E-3-heptene. The lifetime deduced under these conditions is approximate to 300 ps, which is about 20-fold shorter than that of dimethylcarbene in perfluorohexane at ambient temperature. Upon photolysis (254 nm) of oxadiazoline 1a in argon, 4-diazoheptane and 1-methoxydiazoethane are formed. These diazo compounds undergo subsequent photolysis that revealed the formation of methoxy(methyl)carbene and E- and Z-3-heptene. It was not possible to detect DPC in argon at 14 K.
Amino-Substituted Butatrienes: Unusual η<sup>1</sup> Ligands Formed by an Unusual Reaction
═C═C(R′)2}], are isolated from the reaction of diazoalkanes (R′)2C−N2 (R′ = Me, Et, nPr) with alkoxy(amino)allenylidene complexes [(CO)5M═C═C═C(NMe2)OR] (M = Cr, W; R = Me, Et, (−)-menthyl) or with the (alkylthio)(amino)allenylidene complex [(CO)5W═C═C═C(NMe2)SnPr]. These new η1-butatriene complexes are related to Cα phosphine adducts of allenylidene complexes such as [(CO)5WC(PMe3)═C═C(NMe2)Ph}]
双反应(氨基)allenylidene配合物[(CO)5 W═C═C═C(NME 2)2 ]与diethyldiazomethane产生两个产品,环状卡宾络合物(2)由1,2-加成的Et 2 C-N 2到C α -C β的allenylidene配体和η的键1 -butatriene配合物[(CO)5 W C [C(NME 2)2 ]═C═CEt 2 }](3)。复数2会慢慢消除N 2并重新排列为3。相比之下,只有η 1-重氮三烯配合物[(CO)5 M C [C(C(NMe 2)XR]═C═C(R')2 }]从重氮烷烃(R')2 C-N 2(R '= ME等,ñ PR)与烷氧基(氨基)allenylidene配合物[(CO)5 M═C═C═C(NME 2)OR](M =铬,W; R =甲基,乙基,( - ) -薄荷基)或与(烷硫基)(氨基)allenylidene配合物[(CO)5 W═C═C═C(NME