Enantioselective Synthesis of cis- and trans-2(S)-Amino-1-d-indane: Debrominative [1,2]-Hydride Shift Rearrangement by Reduction of cis-2-Azido-1-bromoindane with LiAlD4
摘要:
This article describes the synthesis of the racemic and optically pure forms of (1R,2S)-cis- and (1S,2S)-trans-2-Amino-1-d-indanes 2 {94% ee} and 3 {83% ee} (ee determined by H-2 NMR in chiral liquid crystal PBLG/CH2Cl2, Courtieu, J. et al. J. Am. Chem. Soc. 1995, 117, 6520) prepared by LiAlD4 reduction of (+/-)- and (1S,2S)-trans-2-azido-1-bromomoindane (11) {87% ee} and (+/-) and (1R,2S)-cis-2-azido-1-[(methanesulfonyl)oxy]indane (10) {83% ee}, respectively. Whereas the LiAlD4 reduction of trans-2-azido-1-bromomoindane (11) led to cis-2-amino-1-d-indane 2 by a S(N)2 pathway, exclusively, the reduction of cis-1-bromo derivative 12 gave only small amounts of the S(N)2 product trans-2-amino-1-d-indane (3) (15%) accompanied by 2-amino-2-d-indane (4) (85%) in which the deuterium atom is incorporated in alpha position to the amino group. It was established that the primary amine 4 comes from a stereospecific [1,2]-hydride shift rearrangement, We propose that the azido group is reduced first, and the [1,2]-hydride shift rearrangement prevails over the competitive S(N)2 substitution. The exclusive formation of trans-2-amino-1-d-indane (3) requires cis-2-azido-1-[(methanesulfonyl)oxy]indane (10) where the mesylate assisted by electrophilic Li+ cation switches the deuteride attack to the ester carbon and the direct S(N)2 substitution occurs before the azide is reduced.
A mass spectral investigation of water and acetic acid elimination from 1- and 2-indan derivatives
作者:G. S. Groenewold、M. L. Gross、R. Zey
DOI:10.1002/oms.1210170905
日期:1982.9
AbstractWater and acetic acid eliminations from 1‐ and 2‐indan derivatives have been investigated. Deuterium labeling, high resolution peak matching and the metastable peak analysis capabilities of a high resolution triple analyzer (E B E) mass spectrometer were employed to examine the eliminations. These experiments showed that water was lost from 1‐indanol via 1,2 and 1,3 processes. These results contrast with those obtained for 1‐tetralol, which specifically eliminates water in a 1,4 process involving the benzylic hydrogens. Water elimination from 2‐indanol is preceded by a slow hydroxyl‐benzylic hydrogen exchange and proceeds specifically 1,2. Water losses from both 1‐ and 2‐indanol are characterized by large kinetic energy releases. Acetic acid elimination is shown to occur specifically 1,3 from 1‐acetoxyindan and 1,2 from 2‐acetoxyindan.