Selective hydrosilyation of terminal alkynes and catalytic 1,4-additon of alkynes into conjugated enones by [RuCl2(p-cymene)]2

Abstract

Part Ⅰ은 terminal alkyne의 매우 입체선택적이고 효과적인 hydrosilylation에 대한 연구이다. alkyne의 hydrosilylation은 vinylsilane을 준비하는 가장 간단하고 직접적인 방법이다. Vinylsilane은 유기합성에서 building block이나 중간체로써 다양하게 사용되어지고 있다. 전이금속을 촉매로한 alkyne의 hydrosilylation은 잘 알려진 반응이다. 전이금속을 이용한 대부분의 hydrosilylation은 β-(E)-vinylsilane을 주요생성물로 형성하는 반면에 [RuCl_(2) (p-cymene)]_(2),을 촉매로 한 hydrosilylation은 다양한 terminal alkyne에 대해 β-(Z)- Vinylsilane을 매우 높은 선택성으로 형성하였으며 매우 높은 생성율을 보여주었다. 이 연구과정에서 삼중결합의 β위치에 hydroxy기를 갖는 alkyne에 대해 regioisomer인 α-vinylsilane 만이 형성되는 매우 극적인 directing 효과를 관찰할 수 있었다 Part Ⅱ는 촉매를 이용한 terminal alkyne의 conjugated된 enone으로의 1,4-addition에 대한 연구이다. 전이금속을 이용한 alkyne의 1,4-addition은 매우 실용적이며 중요한 반응이다. 하지만, 지금까지 γ,δ-alkynyl ketone을 한 단계로 합성하는 방법은 보고되어있지 않다. 이 반응은 additive의 존재하에서 중요한 중간체인 ruthenium acetylide 형성을 거쳐 진행된다. 온화한 조건에서 다양한 terminal alkyne의 1,4-addition을 수행한 결과 좋은 수득량을 얻었다. Part Ⅲ는 (S)-(+)-Ν-Boc-coniine의 합성이다. 광학적으로 활성을 띠는 (S)-(+)-coniine이 Ν-Boc으로 protect된 형태로써 L-novaline이라는 아미노산을 출발물질로하여 합성을 하였다. 중요한 단계로써 dialkenyl 화합물을 ring-closing olefin metathesis(RCM)을 이용하였으며, 그에 해당하는 cyclic olefin을 매우 정량적으로 얻을 수 있었다.;Part Ⅰ is highyl stereoselective and efficient hydrosilylation of terminal alkynes. Hydrosilylation of alknes is one of the simplest and the most straightforward preparative methods for vinylsilanes, which have great versatility as building blocks and synthetic intermediates in organic synthesis. It is well-known that hydrosilyation of alkynes is induced by transition metal catalysts. Most hydrosilylation with transition matal catalysts proceed in β(E)-isomer while, with [RuCl_(2)(p-cymene)]_(2), as a catalyst, extremly high regio- and stereoselectivity was observed in the hydrosilylation reaction of various terminal alkynes under mild conditions to afford β-(Z)-vinylsilanes in exellent yields. In the course of the present study, we observed a very interesting and dramatic direting effect when alkynes having a hydroxy group at the β position to triple bond were employed as a substrate. And in these cases regioisomeric α-vinylsilanes were generated with exellent selectivity. Part Ⅱ is the fm exemple of ruthenium catalyzed 1,4-addition of terminal alkynes to conjugated enones. 1,4-addition of alkynes with transition metal complex is a process of great practical importance. However, the corresponding 1,6addition reaction, which provide a one-step synthesis of r,δ-alkynyl ketone, has never been reported. Mechanistic implicate the ruthenium acetylide complex in the presence of additive as a key intermediate. 1,4- addition with various terminal alkynes under mild conditions was accompanied in fairy good yield. Part Ⅲ is synthesis of (S)-(+)-N-Boc-coniine. Optically active (S)-(+)-coniine as an N- Boc protected form was concisely prepared starting from an amino acid, L-notaline. The key step involved a ring-closing olefin metathesis (RCM) of the dialkenyl compound to give the corresponding cylic olefin in an essentially quantitative yield.