A novel stereospecific synthesis of (+)-oxybiotin a biologically active analogue of (+)-biotin has been achieved starting fromd-arabinose through ten synthetic steps.
A novel ten-step synthesis of (+)-oxybiotin, a biologically active analogue of (+)-biotin, has been achieved starting fromd-arabinose.
从d-阿拉伯糖开始,已经实现了(+)-生物素的生物活性类似物(+)-氧生物素的新颖的十步合成。
Synthesis of pyrrolizin-3-ones by flash vacuum pyrolysis of pyrrol-2-ylmethylidene Meldrum’s acid derivatives and 3-(pyrrol-2-yl)propenoic esters
作者:Shirley E. Campbell、Murray C. Comer、Paul A. Derbyshire、Xavier L. M. Despinoy、Hamish McNab、Roderick Morrison、Craig C. Sommerville、Craig Thornley
DOI:10.1039/a701749i
日期:——
Monosubstituted pyrrolizin-3-ones 1 with substituents at the 1-, 5-,
6- or 7-positions are prepared in excellent yield by flash vacuum
pyrolysis (FVP) of appropriate Meldrumâs acid derivatives 2. The
mechanism involves formation of the pyrrol-2-ylmethylideneketene 29,
which can also be generated thermally from 3-(pyrrol-2-yl)propenoate
esters (e.g. 30). This alternative route has been used to make
a range of 2-substituted pyrrolizin-3-ones, again in excellent yield.
The 3-oxo-3H-pyrrolizine-2-carboxylic acid 42 could not be made
in this way owing to facile decarboxylation to pyrrolizinone 1, and
extension to the formation of the azaazulenone 48 was again
unsuccessful.
The present invention relates to compounds of formula (I), in which formula X is hydrogen or hydroxy or protected hydroxy; R1 an R2 stand for hydrogen, methyl or ethyl, or, when taken together with the carbon atom bearing the group X, R1 and R2 can form a C3-C5 carbocyclic ring; Q is a C3-C6 hydrocarbylene, hydrocarbylene indicating the diradical obtained after removal of 2 hydrogen atoms for a straight or banched, saturated or unsaturated hydrocarbon, in which one of any CH2 groups may optionally be replaced by an oxygen atom or a carbonyl group, such that the carbon atom (C-22) directly bonded to C-20 is an sp2 or sp3 hybridized carbon atom, i.e. bonded to 2 or 3 other atoms; and in which another of the CH2 groups may be replaced by phenylene, and where Q may optionally be substituted with one or more hydroxy or C1-C4-alkoxy groups. These compounds have been discovered to possess exceptionally high immunosuppressive activites together with high tumour cell proliferation inhibiting activities.