2- Propyn silylation

Treatment of propyne iminium triflate 258 with silylated phosphorus nucleophiles such as Me3SiPPhR affords (3-morpholinoallenyl)phosphanes 259 in high yield (Scheme 8.69) [150]. 

Trimethylsilyl-2-propyn-l-o1 was obtained from Petrarch Systems, Inc. and used as received. Alternatively, it can be prepared by the silylation of 2-propyn-l-ol ... 

Property Poly[ 1 -(trimethyl-silyl)-l-propyne Poly(dimethyl- siloxane)... 

Five months later, Corey and Lee reported the enantioselective Diels-Alder reaction between cyclopentadiene and a,/ -acetylenic aldehydes catalyzed by a chiral cationic oxazaborinane catalyst [33]. Although initial studies of the Diels-Alder reaction between cyclopentadiene and 2-butyn-l-al or 2-octyn-l-al with 20 mol % catalyst at -94 °C to -78 °C revealed only 3-5 % conversion to product over a 24-h period, replacement of the /3-alkyl substituent on the aldehyde component by RsSi or RsSn groups resulted in much faster Diels-Alder addition (Eq. 33). The greater yield with 3-tributylstannyl-2-propyn-l-al, compared with the 3-silyl analogs, results from the rate of reaction with the former. In each instance, good enantioselectivity (80-87 % ee) was obtained. 

Saccharin pseudochloride 112 (R = C1) reacts with 1-diethylamino-l-propyne to give 113. When the corresponding 3-ethoxy derivative 112 (R = OEt) was treated with the same alkyne, a ring-expansion product 114 (R = OEt) was isolated. On the other hand, the analogous thiazepine 114 (R = OSiMc3) is obtained, together with the ketone derived by hydrolysis of the silyl enol ether, by the reaction of saccharin with BuLi/trimethylsilyl chloride (TMCS)... 

The reaction has been extended to a-silyl lactones and lactams. Other stabilizing groups have been demonstrated to be effective. For example, the Peterson reagent formed from bis(trimethylsilyl)propyne (357) and that formed from a-silyl acetonitrile derivatives (358) both give the (Z)-alkene as the predominant product (equation 84). ... 

Organo-silanes and -stannanes possessing sp caibon-metal bonds also add to carbonyls in the presence of Lewis acids. Alkynylation with silyl- and stannyl-alkynes is promoted by AICI3 or ZtiGz (equations 9 and 10). " Notably, the reaction of l,3-bis(trimethylsilyl)-l-propyne with chloral affords alkynic alcohol instead of allenylic alcohol, showing the preferential cleavage of sp C—Si bonds (equation 11). ... 

Poly (trimethyl-silyl) propyne Largest known solubility of oxygen, candidate for efficient oxidation of CdSe nanocrystals... 

Diastereoselective aldol reactions of propynals.4 The cobalt complex 1 of propynal reacts with O-silyl ketene 0,S-acetate (2) to form the syn aldol almost exclusively. 

Lewis-acid-promoted alkylations of silylenol ethers and silyl ketene acetals [195] with Co-complexed acetylenic acetals [196] and acetylenic aldehydes [197,198] (Scheme 4-56) also proceed with fair to excellent syn diastereoselectivity, in contrast to the low selectivity reactions of the free acetylenic derivatives [199, 200]. Reactions of the complexed aldehydes with lithium enolates are stereospecific, with (Z)-enolates giving syn selectivity and ( )-enolates anti selectivity [201]. The complementary stereoselectivity of the crossed aldol reactions of free and cobalt-complexed propynals with silyl ketene 0,S-acetals has been elaborated by Hanoaka exclusive syn selectivity is exhibited by the complexes and high anti selectivity is found with pro-... 

Silylated enynes. Condensation of 3,3-bis(trimethylsilyl)propyne with aldehydes provides predominantly ( )-l-trimethylsilylalk-3-en-l-ynes (8 examples, 48-60%). 

Fusaoka et al. [12] observed a structure composed of fused and deformed polymeric spheres using FE-SEM in a cross section of the membranes, cast and dried from solutions of poly(l-trimethyl-silyl-l-propyne), poly(4-methyl-l-pentene), and some other polymers. 

Nakagawa, T., The Highest Gas Permeable Membranes of Poly[l-(trimeth silyl)-1-propyne]—Their Gas Permeability and Modification. In Science and Technology of Polymers and Advanced Materials, Prasad, P. N. Mark, J. E. KandU, S. H. Kafafi, Z. H., Eds. Plenum Press New York, 1998 pp 821-834. 

Alkynyltriisopropylsilanes. The acidic alkynic H can be protected with TIPS triflate. Silylation of 1-lithiopropyne with 1 equiv of TIPS triflate in ether at —40 to 0 °C gives an 87% yield of 1-TIPS-propyne (eq 4). l,3-Bis(triisopropylsilyl)propyne, derived from treatment of 1-TIPS-propyne with butyllithium in THF at —20 °C for 15 min followed by TIPS triflate at —78 to —40°C (eq 5), is lithiated with n-BuLi in THF at —20°C for 15 min and then allowed to react with aldehydes (eq 6). The cjs enynes are isolated in high yields. TlPS-propargylmag-nesium bromide together with copper(I) iodide has been used in the displacement of the mesylate derivative of farnesol. ... 

Scheme 10 9. A scheme showing a representation of what occnrs on treatment of 2-propyne-l-ol (propargyl alcohol) with dihydropyran (oxacyclohex-2-ene) in the presence of an acid catalyst followed by n-bntyllithinmin hexane at-30°C and then with f-bntyldimethylchlorosilane [(CH3)3CSi(CH3)2Cl] after the temperatnre is lowered to -78°C. The silylated prodnct on treatment with methanolic acid generates the corresponding free alcohol with the trimethyl-silyl group in place.

In a similar manner, allenylborane derived from 3-(tert-butyldimethylsilyl)-l-(trimethylsilyl)-propyne gives mainly (lS,2i )-2-(fert-butyldimethylsilyl)-l-[2-(3-methyl-3-buten-l-ynyl)-l-cyclopentenyl]-4-(trimethylsilyl)-3-butyn-l-ol (54%) and (lS,2i )-2-(ferf-butyldimethylsilyl)-l-[2-l-cyclohexenylethynyl)-l-cyclopentenyl]-4-(trimethyl silyl)-3-butyn-l-ol (55%) (Chart 6.17) [1]. 

Nagase et al. have studied the grafting of polyacetylene and its derivative onto poly(dimethylsiloxane) (PDMS) for membrane applications [118-121]. Poly(l-trimethyl-silyl-l-propyne) (PTMSP) is a polymer known to have excellent gas permeability but suffers from relatively low selectivity and a decrease in gas permeability over time. Graft copolymers of poly(l-phenyl-1-propyne) (PPP) onto PDMS were found to have improved gas permeability and selectivity, and the performance was related non-linearly to the PDMS content. A minimum oxygen permeability coefficient was found for a copolymer with 55 mol% PDMS [118]. The same membrane series was also foimd to be permselective for a range or organic liquids, including an ethanol/water mixture, and was used in pervaporation applications... 

Preparative Method l,3-bis(TIPS)propyne is prepared in quantitative yield by silylation of 3-lithio-l-triisopropylsilyl-l-propyne with triisopropylsilyl trifluoromethanesulfonate. ... 

Enynes and Dienynes from Other Bis(silyl)propynes. 

Reagent (1) is made by deprotonation of l-TIPS-prop)me using -butyllithium in ether, better without than with TMEDA added, or f-butyllithium in ether/pentane, or preferably -BuLi in THE (—20°C, 15 min). 1-TIPS-propyne can be prepared from propyne by silylation of either its lithio derivative using TIPS triflate or of the bromomagnesium derivative using TIPS chloride it is also commercially available. 

Bis(silyl)propyne. Reaction of (1) with sUylating agents affords l,3-bis(silyl)propynes, valuable Peterson reagents (eq 16). ... 

---