Trimethylsilyl-2 -propyn--l-ol

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

The suspension 1s cooled to 20°C on 1ce and then 800 mL of 1.4 M aqueous sulfuric acid is cautiously added over 0.75 hr so that the temperature remains below 45°C. The resulting solution is stirred for 5 min and then 600 mL of ether is added. Both phases are transferred to a 4-L separatory funnel and the layers are separated. The aqueous phase is extracted twice with 400-mL portions of ether and all ether layers are individually washed in series with two 1-L portions of water and once with 800 mL of saturated sodium chloride solution. The combined organic extracts are dried over magnesium sulfate and concentrated by rotary evaporation. The yellow-brown residue is purified by short path distillation to afford 82-86 g (91-94 yield) of 3-trimethylsilyl-2-propyn-l-ol as a clear, colorless liquid (Note 7), bp 76°C (20 mm) (Note 8). 

Furanes. Hydromagnesiation of 3-trimethylsilyl-2-propyne-l-ol (1) (11, 163) followed by reaction with an aldehyde or ketone provides E-3-lrimethylsilyl-2-alkcne-l,4-diols (2). These are converted into 3-trimethylsilyl-2,5-dihydrofurancs (3) on dehydration... 

Reduction of propargyl alcohols. 3-Trimethylsilyl-2-propyne-l-ol (1), prepared as shown from propargyl alcohol, is reduced stereospecifically by SMEAH to (E)-3-trimethylsilyl-2-propene-1-ol (2). Reductions of propargyl alcohols with LiAIH4 are less rraws-selective. 

B. (EJ-S-Trimethyteilyl-S-ppopen-l-ol, A three-necked, 2-L, round-bottomed flask fitted with a thermometer, nitrogen inlet, 250-mL pressureequalizing addition funnel, and a magnetic stirring bar is charged with 147 mL of a 3.4 M solution of sodium bis(2-methoxyethoxy)aluminum hydride (SMEAH, Note 9) and 200 mL of anhydrous ether (Note 10). The SMEAH solution is cooled to 3°C on ice and then treated dropwise from the addition funnel with a solution of 40 g (0.31 mol) of 3-trimethylsilyl-2-propyn-l-ol in 180 mL of ether over 1.25 hr maintaining the temperature at 5 C or less. Ten minutes after complete addition the ice bath is removed and the reaction is complete... 

Trimethylsilyl-3-rnethylthio-l-propyne, 54 - (32) Trimethyl-silylacetylene, 55 - (32) Bis(trimethylsilyl)acetylene, 56 - (33) 1--Ethoxy-2-trimethylsilylacetylene, 57 - (34) 3-Trimethylsilyl-2 -propyn--l-ol, 58 - (35) 2-Butynoic acid, 59 - (3S) Methyl-1-propynyl sulfoxide,... 

Preparative Methods (i) from 3-trimethylsilyl-2-propyn-l-ol by reduction (sodium bis(2-methoxyethoxy) aluminum hydride (Red-Al), 70%) and acetylation (acetyl chloride, pyridine, 78%) (ii) from 3-trimethylsilyl-2-propyn-l-ol by reduction (P-2 raney nickel, H2, 86%) and acetylation (iii) from ally-loxytrimethylsilane by a metalation-rearrangement sequence (f-butyllithium, 90%) and acetylation (acetic anhydride, triethylamine, 76%). ... 

As model compounds we have chosen (3-hydroxy-l-propenyl)tris(trimethylsilyl)silanes (4a-c), which were obtained by AIBN-initiated additions of tris(trimethylsilyl)silane (3) to propargylic alcohol, 2-methyl-3-butyn-2-ol and l,l-diphenyl-2-propyn-l-ol, respectively (Eq. 1). In agreement with literature data [3], in the case of the reaction of 3 with propargylic alcohol the Z-olefin 4a was obtained. NMR studies of 4b and 4c revealed an E-configuration for the two olefins. 

Preparative Method the first reported preparation of this reagent lacked full experimental details. The preparation given (eq 1) is a compilation of the work of several groups the various steps have been selected to give optimum yields. 2-Propyn- l-ol is converted into its 3-(trimethylsilyl) derivative (1), which is then reduced using sodium bis(2-methoxyethoxy)aluminum... 

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]. 

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