Trimethylsiloxy-2-Pentene

Submitted by Isaq Klwajima, Eiichi Nakamura and Koichi Hashimoto Checked by Peter J Card and Richard E Benson 

1 This procedure is based on a report by Fessenden and Fessenden Cuprous chloride is a more efficient initiator than iodine as specified in the original procedure 

2 The submitters used zinc powder purchased from Koso Chemical (Japan) without any punfication The checkers used product available from Fisher Scientific Company It is essential to use excess zinc to ensure complete consumption of ethyl bromoacetate which interrupts the catalytic cycle in step B of the present silylation reaction 

3 The submitters used cuprous chlonde purchased from Koso Chemical Co Ltd without purification The checkers used cuprous chlonde available from Fisher Scientific Company 

4 The submitters used diethyl ether, obtained from Showa Ether, after distillation from sodium wire The checkers distilled the product obtained from Fisher Scientific Company from lithium aluminum hydride 

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It should be noted that the reaction of benzalde-hyde with (Z)-3-trimethylsiloxy-2-pentene in ethanol or dichloromethane in the presence of the chiral catalyst resulted in a much lower yield and selectivity. On the basis of these results, we propose the catalytic cycle shown in Scheme 2. The catalyst A formed from Cu(OTf)2 and a bis(oxazoline) ligand accelerates the aldol reaction to generate the intermediate B. In aqueous solvents, B is rapidly hydrolyzed to produce the aldol product C and regener-... 

Z)-3-Trimethylsiloxy-2-pentene Silane, [(1 -ethyl-1-propenyl)oxy]tri-methyl-, (Z)-(9) (51425-54-8)... 

A practical synthesis of 1,3-OX AZEPINES VIA PHOTOISOMERIZATION OF HETERO AROMATIC V-OXIDES is illustrated for 3,1-BENZOXAZEPINE. A hydroboration procedure for the synthesis of PERHYDRO-9b-BORAPHENALENE AND PERHYDRO-9b-PHEN-ALENOL illustrates beautifully the power of this methodology in the construction of polycyclic substances. The conversion of LIMONENE TO p-MENTH-8-EN-YL METHYL ETHER demonstrates a regio-and chemoselective method for the PHOTOPROTONATION OF CYCLOALKENES. An efficient method for the conversion of a ketone to an olefin involves REDUCTIVE CLEAVAGE OF VINYL PHOSPHATES. A mild method for the conversion of a ketone into the corresponding trimethylsiloxy enol ether using trimethylsilyl acetate is shownforthe synthesis of (Z)-3-TRIMETHYLSILOXY-2-PENTENE. 

SILYLATION OF KETONES WITH ETHYL TRIMETHYLSILYLACETATE (Z)-3-TRIMETHYLSILOXY-2-PENTENE... 

While the aldol reaction of benzaldehyde with (Z)-3-trimethylsiloxy-2-pentene proceeded smoothly in water-ethanol (1 9) at -15 C to afford the desired adduct in a high yield with good selectivities (quant., syn/anti-33/, syn=15% ee), much lower yield and selectivities were observed in ethanol (without water) under the. same conditions (10% yield, synfanti=2.3l, , vyn=41% ee). Furthermore, when the reaction was performed in dichloromethane at -15 °C, the aldol adduct was obtained in 11% yield with syn/anti=2.ll [.yy =20% ee (the opposite absolute configuration)]. From these results, we assume that desired chiral reactions are accelerated by water and that undesired achiral side reactions which proceed rapidly in aprotic solvents [32] are suppressed in aqueous media. 

Trimethylsiloxy-2-pentene, 227 Trimethylsilylacetic acid, 509 Trimethylsilylacetyl chloride, 509 Trimethylsilylarenes, 514 Trimethylsilyl carbamates, 263 Trimethylsilylcarbene, 307-308 Trimethylsilyl cyanide, 133... 

SUylation. Details are available for conversion of 3-pentanone (1) into (Z)-3-trimethylsiloxy-2-pentene (2) in the presence of tetra- -butylammonium fluoride (a preparation of this salt is included). ... 

The average 14C KIEs for the rearrangement of 234a to l-(trimethylsiloxy)-4-pentenal 235a in THF at22°C are ... 

Moreover, the formation of enoxy-silanes via silylation of ketones127 by means of N-methyl-N-TMS-acetamide (1 72) in presence of sodium trimethylsilanolate (173) was reported in 1969 and since then, the use of silylating reagents in presence of a catalyst has found wide appreciation and growing utilization as shown in recent papers128-132 (Scheme 27). Diacetyl (181) can be converted by trifluoromethylsul-fonic acid-TMS-ester (182) into 2,3-bis(trimethylsiloxy)-l, 3-butadiene (7treatment with ethyl TMS acetate (7 5)/tetrakis(n-butyl)amine fluoride l-trimethylsiloxy-2-methyl-styrene (i<56)130. Cyclohexanone reacts with the combination dimethyl-TMS-amine (18 7)/p-toluenesulfonic acid to 1-trimethylsiloxy-l-cyclohexene (iSS)131. Similarly, acetylacetone plus phenyl-triethylsilyl-sulfide (189) afford 2-triethylsiloxy-2-pentene-4-one (790)132. ... 

We have recently demonstrated that a variety of functionalized olefins can be polymerized with these new cationic metallocenes. Catalysts derived from the reaction of Cp 2ZrMe2 with B(C6F5)3 or [PhNHMe2]" [B(C6F5)4] are active for the homopolymerization of the functionalized monomers 4-(TMSO)-l,6-heptadiene (5) (TMSO = trimethylsiloxy), l-(TBSO)-4-pentene (6) (TBSO = rm-butyldimethylsiloxy) and N,N-diisopropyl-4-penten-1-amine (7) (Scheme 6). 

A mixture of 3-methyl-2,4-pentanedione, hexamethyldisilazane, and imidazole stirred and heated 4-8 hrs. at 70 2-trimethylsiloxy-3-methyl-2-penten-4-one. Y 96%. F. e. s. S. Torkelson and C. Ainsworth, Synthesis 1976, 722. 

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