The reactions of the singlet methylene (la) and dimethylcarbene (1b), with their diazirine precursors, diazirine (2a), and dimethyldiazirine (2b), have been studied theoretically using ab initio and density functional theory. The reaction has no activation barriers for the parent system (la + 2a) an...

An ultraviolet photoelectron (PE) spectrometer apparatus that utilizes a tuneable 50 W CW CO2 laser as a directed heat source was used to study the vacuum pyrolysis of diazoacetophenone (la) and its p-methyl, p-methoxy, p-chloro, and p-nitro analogues Ib, Ic, Id, and le. Analysis of the pyrolysate w...

Rearrangements of 2-adamantene 3, adamantylidene 4, and 4-protoadamantylidene 5 have been studied theoretically using high level ab initio computations. Adamantene 3 and adamantylidene 4 have singlet ground states. The conversion of 3 into 4 via 1,2 hydrogen migration (Delta G(not equal) = 69.1 kcal...

N-Protonated diazomethanes have been generated successfully via gas phase protonation of the corresponding diazirines.

Benzylchlorocarbene (1, BCC) was generated photochemically from benzylchlorodiazirine (2) in isooctane, methylcyclohexane (MCH), and tetrachloroethane (TCE) at temperatures from similar to 30 to -75 degrees C. At -70 degrees C in isooctane, the identified products included Z/E-beta-chlorostyrenes 4 ...

The stereochemistry of 1,2-H migration in ethylchlorocarbene (1) and chloromethylchlorocarbene (2) has been studied by ab initio methods. Geometries of the ground and transition states of a conformational equilibrium and the 1,2 rearrangement were optimized at the DFT (B3LYP) and MP2 levels of theor...

Laser flash photolysis of 3-chloro-3-benzyldiazirine and 3-chloro-3-(phenyldideuteriomethyl)diazirine in isooctane over the 60 to -80-degrees-C temperature range gives rise to curved Arrhenius plots for both 1,2-H and 1,2-D migration in benzylchlorcarbene. The k(H)/k(D) values increase smoothly from...

Nanosecond laser flash photolysis (lambda = 355 nm) of an aqueous solution of 3-chloro-3-p-chlorophenyldiazirine in isooctane produces a transient absorption at 310 nm due to the formation of the carbene: In the presence of 2-vinylpyridine, a second transient with a broad absorption band peaking at ...

When photolysis of arylchlorodiazirines is performed in the presence of either alkyl- or allyl-substituted amines, either N-alkyl- or N-allyl-substituted amines result as the sole high-yield (64-93%) products. Photolysis in the presence of phenylallylamine produces a rearranged product in poor yield...

The crystal structure and electron density of 3-[(p-nitrophenoxy)methyl]-3-chlorodiazirine have been analyzed using single crystal X-ray diffraction at 208 K with Mo K alpha radiation to a resolution of sin(theta(max))/lambda = 1.126 Angstrom(-1). A total of 10 440 measured reflections gave 7742 uni...

p-Chlorophenylchlorocarbene reacts with allyl bromide to form the expected cyclopropanes. In the case of p-nitrophenylchlorocarbene, a small amount of insertion product is also formed in addition to the cycloadducts. The formation of the insertion product is attributed to the attack of the carbene o...

The combination of laser flash photolysis and product analysis demonstrates that even though (phenoxymethyl)chlorocarbene reacts with its diazirine precursor with a substantial rate constant of 3.5 x 10(8) M(-1)s(-1), the predicted azine product is not formed. These results indicate either carbene/d...

3-Substituted indolizines have been obtained in a one-step procedure from the reaction of chlorocarbenes with 2-vinylpyridine.

The first determination of a 1,2-phenyl shift in alpha,alpha-dimethylbenzylchlorocarbene was achieved by nanosecond laser flash photolysis, tau = 50 ns.

Photolysis of 3-benzyl-3-chlorodiazirine and its deuterated homologues 3-chloro-3-(phenyldideuteriomethyl)diazirine and 3-chloro-3-((pentadeuteriophenyl)methyl)diazirine has been investigated by means of IR and UV-vis spectroscopy in argon and xenon matrices. Parent benzylchlorocarbene was produced ...

An alternative method for the generation of arylchlorocarbenes using ultrasound is described.

Phenylchlorocarbenes, produced by photolysis of the parent diazirines, have a very limited lifetime in alkane solvents. The rate of disappearance of p-methyl- and p-chlorophenylchlorocarbenes has been measured in iso-octane, cyclohexane and n-hexane as well as in benzene for comparison. The rate con...

The first direct determination of a 1,2-chlorine atom shift in a chlorobenzylcarbene was achieved by nanosecond laser flash photolysis. Arrhenius activation parameters of E(act) = 3.39 +/- 0.14 kcal mol-1 and log [A(s-1)] = 10.98 +/- 0.14 were obtained for 1,2-chlorine migration in alpha-methyl-alph...

Laser flash photolysis of para-substituted 3-chloro-3-benzyldiazirines in isooctane produces the corresponding carbenes, which react with pyridine to form ylides or undergo 1,2-H migration to form the (Z)- and (E)-beta-chlorostyrenes. The rate for the 1,2-H migration is determined by plotting the ps...

Photolysis of 3-chloro-3-benzyldiazirine in tetramethylethylene gives E- and Z-beta-chlorostyrenes and cyclopropane. Relative rate studies show that the styrenes to cyclopropane ratio increases with increasing diazirine concentration. This permits the determination of the ratio k(D)/k(i) = 8 where k...