Carbethoxynitrene

Abstract

0 CD3 CDs dc (3.3), di (0.2) 3.90 6.0 60.1 6.0 6.21 f 0.02 1.05 5.63 6.0 4.0 0.32 6.70 f 0.01 1.13 dlo (69.7), dg (25.0) 9.60-9.63 9.59 6.0 60.1 0.35 6.99 f 0.01 1.18 de (3.9), ds-7 (1.4) CDJ CDI Corresponding to the major constituent. Measurements were kindly performed by Mr. E. Miller, using a CEC type 21-103C instrument operated at 7-8 e.v. A = aromatic multiplet with center peak a t r = 2.8-2.9; B = methylene peak, T = 7.4; C = methyl singlet, T = 7.7-7.8. Measurements were made using a Varian A-60 spectrometer and -10% w./v. solutions in CDCll with TMS as internal standard. e Determined polarimetrically (X 435 mfi, 12 dm.) on benzene solutions (c 1-5) a t 42.0 * 0.1'. In each case the listed average and standard error were computed by a nonlinear least squares analysis of readings taken over a span of three half-lives. Determined by Mr. J. Nemeth, Urbana, Ill., using the falling drop method.

Synthesis of Antiproliferative Cephalotaxus Esters and Their Evaluation against Several Human Hematopoietic and Solid Tumor Cell Lines: Uncovering Differential Susceptibilities to Multidrug Resistance

“…Although the all-carbon divinyl cyclopropane rearrangement has received the most attention, the heterocyclic epoxide-, thiirane-, and aziridine-containing variants are also documented. [39] However, the aziridine-to-azepine version of this transformation [40][41][42][43][44][45][46] has only been sporadically used in target-directed synthesis. In this context, adaptation to the synthesis of benzazepines and heterocyclic variants thereof have focused on N-aryl-2-vinyl aziridines to form dihydro [1]benzazepines.…”

Total Synthesis of the Marine Natural Product rac‐Dibromophakellstatin

“…We then analyzed the reactivity of the nitrenes generated from the sources 5 and 6 (Figure 2) towards the tricyclic acylenamine 3 14. 15 Compound 5 would provide an isourea‐derived nitrene, which could first add electrophilically to C10.…”

“…The goal of assembling the ABCD tetracycle was achieved by reaction of the tricycle 3 with ethyl N ‐tosyloxycarbamate ( 6 ) in the presence of calcium oxide 17. In the first step deprotonation of the urethane 6 at room temperature generates the corresponding nitrene by α‐elimination of tosylate 14. One of the compounds in the product mixture turned out to be the alkenyl carbamate 13 , the structure of which was confirmed by X‐ray analysis (Scheme , Figure 4).…”

Azictes. Part VI. Thermolysis of ethyl azidoformate in dimethyl terephthalate; formation of a diazabicyclooctadiene heterocycle

“…The synthesis of azepines using the nitrene generated from azidoformate has also been reported by Hafner and Konig (3) and Lwowski et al (4). These authors have mainly dealt with the nitrene insertion into aromatic substrate bearing electron-donating substituents.…”

“…Ethyl N -(2,5-dicarbomethoxyphenylicarbarnate (4) A mixture of dimethyl aminoterephthalate (0.1 g, 0.00048 mol), ethyl chloroformate (100 rnL) and sodium carbonate (0.1 g) was refluxed for 16 h. Excess ethyl chloroformate was distilled off under reduced pressure. The residue was recrystailised from petroleum ether to yield colourlecs needles of the carbamate (4, (0.05 g, 43%).…”