Diastereoselective bromine/lithium-exchange applied to the synthesis of a C-1/C-9-segment of the bryostatins
作者:Reinhard W Hoffmann、Hans Christian Stiasny
DOI:10.1016/0040-4039(95)00821-s
日期:1995.6
The α-bromo-alkyllithium compounds 5 are generated by diastereoselective bromine/lithium exchange on the dibromo-compound 4. The minor carbenoid 5b generated cyclizes spontaneously at −110°C to the bicyclo[3.1.0]hexane 6, thus, leaving the major carbenoid 5a in diastereomerically pure form. Application of the boronate extension reaction to this carbenoid 5a ed to 1,3- or 1,6-diol derivatives, viz.
Reactivity of α-Bromosulfones Obtained from<i>gem</i>-Dibromides
作者:Niels Münster、Laura Werel、Georg Alexander Rennar、Klaus Harms、Ulrich Koert
DOI:10.1002/ejoc.201501136
日期:2015.12
α-Bromosulfones have been synthesized diastereoselectively by reaction of β-hydroxy gem-dibromides with aromatic sulfinates. More steric demanding groups in the β-position led to increased stereoselectivity in these SN2 reactions. Lithiated α-bromosulfones react diastereoselectively with alkylating agents, aldehydes, and ketones. No configurational stability of the lithiated α-bromosulfones was observed
Stiasny, Hans Christian; Hoffmann, Reinhard W., Chemistry - A European Journal, 1995, vol. 1, # 9, p. 619 - 624
作者:Stiasny, Hans Christian、Hoffmann, Reinhard W.
DOI:——
日期:——
Synthesis of 1,1-Dibromo-3-hydroxyalkanes via Opening of Cyclic Sulfates
作者:Hans Christian Stiasny
DOI:10.1055/s-1996-4193
日期:1996.2
3-Alkoxy-1,1-dibromoalkanes are interesting substrates for diastereoselective bromine/lithium exchange reactions. A general route to the precursor 1,1-dibromo-3-hydroxyalkanes is described here via reaction of dibromomethyllithium with cyclic sulfates of 1,2-diols.
Diastereoselective bromine/lithium exchange reactions of 3-alkoxy-1,1-dibromo-alkanes
作者:Reinhard W. Hoffmann、Hans-Christian Stiasny、Jochen Krüger
DOI:10.1016/0040-4020(96)00260-8
日期:1996.5
The diastereoselectivity in the bromine/lithium exchangereaction on chiral 3-alkoxy-1,1-dibromo-alkanes has been investigated. The differentiation of the two diastereotopic bromine atoms was found not to depend solely on a conformational preorganisation of the substrate, as surmised previously. It became apparent that steric crowding at the δ-center controls the spatial orientation of a C-3-oxygen