Platinum-catalyzed double silylations of alkynes with bis(dichlorosilyl)methanes

다국어 초록 (Multilingual Abstract)

<P><B>Graphical abstract</B></P><P>Reaction of alkynes such as ethene (<B>2a</B>), phenylethene (<B>2b</B>); 1,2-diphenylethene (<B>2c</B>) with bis(dichlorosilyl)methanes RCH(SiHCl<SUB>2</SUB>)<SUB>2</SUB>: R=H (<B>1a</B>), SiMe<SUB><I>n</I></SUB>Cl<SUB>3−<I>n</I></SUB>: <I>n</I>=0 (<B>1b</B>), 1 (<B>1c</B>), 2 (<B>1d</B>), 3 (<B>1e</B>) in the presence of Speier’s catalyst gave one of two type products of 1,3-disilacyclopentanes <B>3</B> and 1,3-disilacyclopent-4-enes <B>4</B>. Reaction of <B>1a</B> with <B>2a</B>–<B>c</B> at 80°C gave compounds <B>3</B> in 33–84% yields. The reaction with <B>2c</B> gave <B>3ac</B> in the highest yield (84%). Reaction of <B>1b</B>–<B>e</B> with <B>2c</B> under the same conditions gave compounds <B>3</B> in 38–98% yields. The yields deceased in following order: <I>n</I>=1>2>3>0. Reactions of <B>1c</B> with simple <B>2a</B> and terminal <B>2b</B> under the same conditions gave <B>4ca</B> and <B>4cb</B> in 91% and 57% yields, respectively, while internal alkyne <B>2c</B> afforded <B>3cc</B> in 98% yield.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>Bis(dichlorosilyl)methanes <B>1</B> undergo the two kind reactions of a double hydrosilylation and a dehydrogenative double silylation with alkynes <B>2</B> such as acetylene and activated phenyl-substituted acetylenes in the presence of Speier’s catalyst to give 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes <B>4</B> as cyclic products, respectively, depending upon the molecular structures of both bis(dichlorosilyl)methanes (<B>1</B>) and alkynes (<B>2</B>). Simple bis(dichlorosilyl)methane (<B>1a</B>) reacted with alkynes [R<SUP>1</SUP>–CC–R<SUP>2</SUP>: R<SUP>1</SUP>=H, R<SUP>2</SUP>=H (<B>2a</B>), Ph (<B>2b</B>); R<SUP>1</SUP>=R<SUP>2</SUP>=Ph (<B>2c</B>)] at 80°C to afford 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> as the double hydrosilylation products in fair to good yields (33–84%). Among these reactions, the reaction with <B>2c</B> gave a <I>trans</I>-4,5-diphenyl-1,1,3,3-tetrachloro-1,3-disilacyclopentane <B>3ac</B> in the highest yield (84%). When a variety of bis(dichlorosilyl)(silyl)methanes [(Me<SUB><I>n</I></SUB>Cl<SUB>3−<I>n</I></SUB>Si)CH(SiHCl<SUB>2</SUB>)<SUB>2</SUB>: <I>n</I>=0 (<B>1b</B>), 1 (<B>1c</B>), 2 (<B>1d</B>), 3 (<B>1e</B>)] were applied in the reaction with alkyne (<B>2c</B>) under the same reaction conditions. The double hydrosilylation products, 2-silyl-1,1,3,3-tetrachloro-1,3-disilacyclopentanes (<B>3</B>), were obtained in fair to excellent yields (38–98%). The yields of compound <B>3</B> deceased as follows: <I>n</I>=1>2>3>0. The reaction of alkynes (<B>2a</B>–<B>c</B>) with <B>1c</B> under the same conditions gave one of two type products of 1,1,3,3-tetrachloro-1,3-disilacyclopentanes <B>3</B> and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes (<B>4</B>): simple alkyne <B>2a</B> and terminal <B>2b</B> gave the latter products <B>4ca</B> and <B>4cb</B> in 91% and 57% yields, respectively, while internal alkyne <B>2c</B> afforded the former cyclic products <B>3cc</B> with <I>trans</I> form between two phenyl groups at the 3- and 4-carbon atoms in 98% yield, respectively. Among platinum compounds such as Speier’s catalyst, PtCl<SUB>2</SUB>(PEt<SUB>3</SUB>)<SUB>2</SUB>, Pt(PPh<SUB>3</SUB>)<SUB>2</SUB>(C<SUB>2</SUB>H<SUB>4</SUB>), Pt(PPh<SUB>3</SUB>)<SUB>4</SUB>, Pt[ViMeSiO]<SUB>4</SUB>, and Pt/C, Speier’s catalyst was the best catalyst for such silylation reactions.</P>