540-47-6Relevant academic research and scientific papers
Deamination Reactions, 42. Addition of Diazocyclopropanes to Carbonyl Compounds
Kirmse, Wolfgang,Hellwig, Georg,Chiem, Pham van
, p. 1511 - 1524 (2007/10/02)
Diazocyclopropanes (6, 38, 57) were generated in equilibrium with cyclopropanediazonium ions by base-induced cleavage of the analogous nitrosoureas in methanol.Efficient trapping of the diazocyclopropanes occurred in dilute solution with a slight excess of carbonyl compounds.The reactivity of the resulting 1-(α-hydroxyalkyl)cyclopropanediazonium ions (10) depended strongly on the α-substituents.Pinacol rearrangements predominated with aldehyde adducts, the migratory aptitudes being H > Ph > CH3.These 1,2-shifts are thought to proceed with inversion at the terminus - the preferred exo-attack of acetaldehyde at 7-diazonorcarane (38) led to the endo-ketone 40.The major product derived from the acetone adduct 22 was the epoxide 26 whose reaction(s) with metanol were also examined.The intramolecular addition of 8-diazobicyclooctan-4-one (57) gave rise to 6-methoxybicyclooct-4-en-1-ol (60).Due to steric constraints, the intermediate 58 underwent exclusive cyclopropyl-allyl transformations (otherwise a minor reaction).
Deamination Reactions, 44. Decomposition of 1-Alkylcyclopropanediazonium Ions
Kirmse, Wolfgang,Rode, Jutta,Rode, Klaus
, p. 3672 - 3693 (2007/10/02)
1-Methyl- (17), 1,2-dimethyl- (41, 44), 1-propyl- (64), 1-(1-methylethyl)cyclopropanediazonium ions (80), and -1-diazonium ions (93) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol.Cyclopropyl-allyl transformation and nucleophilic displacement were the only reactions of 17, 41, 44, and 93 while elimination and 1,2-shifts of an α-hydrogen compete increasingly with 64 and 80.The stereochemistry of ring cleavage and nucleophilic displacement has been explored, using 2-D labels in the case of 17 and 93.Cyclopropanediazonium ions (1) and 41 react stereospecifically, 17 and 44 are moderately stereoselective (ca. 85:15), and 93 is entirely unselective.The data indicate a gradual changeover from concerted to stepwise mechanisms.Appreciable stabilization of the positive charge is required to reach the SN1 extreme.
Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
Kirmse, Wolfgang,Jansen, Ulrich
, p. 2607 - 2625 (2007/10/02)
Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
