99439-82-4Relevant academic research and scientific papers
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.
Enantioselective Preparation of 3-Substituted-4-pentenoic Acids via the Claisen Rearrangement
Kurth, Mark J.,Decker, Owen H. W.
, p. 5769 - 5775 (2007/10/02)
Asymmetric C-C bond formation via the diastereoselective aza-Claisen rearrangement of N-allylketene N,O-acetal 4 is described.The starting materials, allylic alkylating agant 1 and optically pure oxazoline 2, are easily prepared and, in a one-pot procedure, generate rearranged oxazolines 5 in 52-94percent diastereomeric excess.The overall chemical yields for 2 -> 5 range from 51 to 78percent.The aza-Claisen rearrangement (4 -> 5) proceeds with excellent N,O-acetal face selectivity and with good to excellent chair selectivity.Hydrolysis of rearranged oxazoline 5 completes an enantioselective synthesis of 3-substituted pent-4-enoic acids.
