Regioselective Short Synthesis of Epiisoborneol Neopentyl Ether as Chiral Auxiliary: An Absolute Configuration Reset,Helvetica Chimica Acta

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Regioselective Short Synthesis of Epiisoborneol Neopentyl Ether as Chiral Auxiliary: An Absolute Configuration Reset
Helvetica Chimica Acta ( IF 1.5 ) Pub Date : 2021-09-14 , DOI: 10.1002/hlca.202100142
Anna Piatek ₁ , Christian Chapuis ₂

Affiliation

The regio-selective four step synthesis of (1S,2R,3S,4R)-4,7,7-trimethyl-3-(neopentyloxy)bicyclo[2.2.1]heptan-2-ol, as recognized efficient chiral auxiliary, is presented. The strategy based on opening of the key acetal 15 (=(2S,3aR,4S,7R,7aS)-2-tert-butyl-4,8,8-trimethylhexahydro-2H-4,7-methano-1,3-benzodioxole) thus circumvents the poor reactivity of the neopentyl electrophile under alkylation conditions. Following the same strategy, but using the unreported acetal 22 (=(2R,3aS,4S,7R,7aR)-2-tert-butyl-4,8,8-trimethylhexahydro-2H-4,7-methano-1,3-benzodioxole), the corresponding unreported bis-endo alcohol 23 (=(1R,2R,3S,4S)-3-(2,2-dimethylpropoxy)-4,7,7-trimethylbicyclo[2.2.1]heptan-2-ol) could be isolated only in poor yield. An alternative regioselective synthesis, including an ultimate endo-reduction remains to be found. Several erroneous chiroptical properties from the literature are corrected.

中文翻译：

表异冰片新戊醚作为手性助剂的区域选择性短合成：绝对配置重置

(1 S ,2 R ,3 S ,4 R )-4,7,7-三甲基-3-(新戊氧基)双环[2.2.1]庚烷-2-醇的区域选择性四步合成，被认为是有效的手性助剂，提出。基于键的开口缩醛策略15（=（2小号，图3a - [R，4小号，7 - [R，7α小号）-2-叔丁基- 4,8,8-trimethylhexahydro-2 ħ -4,7- methano-1,3-benzodioxole) 因此避免了新戊基亲电试剂在烷基化条件下的不良反应性。遵循相同的策略，但使用未报告的缩醛22 (=(2 R ,3aS ,4 S ,7 R ,7a R )-2-叔丁基-4,8,8-trimethylhexahydro-2 H -4,7-methano-1,3-benzodioxole)，相应的未报道的双内醇23 (=(1 R ,2 R ,3 S ,4 S )-3-(2,2-二甲基丙氧基)-4,7,7-三甲基双环[2.2.1]庚烷-2-醇)屈服。另一种区域选择性合成，包括最终的内还原仍有待发现。纠正了文献中的几个错误的手性特征。

更新日期：2021-11-15

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