1- -l-trimethylsilyl

Organo-tin and -zinc Reagents Derived from 3-lodo-2-l(trimethylsilyl)methyl]propene... 

Hydroboration of Silylalkenes and SUylalkynes. (Z)-l-Trimethylsily 1-1-alkenes react with DBBS to produce ge/rniime-talloalkanes, which upon oxidation afford alcohols containing the trimethylsilyl group in high yields (72-84%) (eq 13). Unexpectedly, desilylation of (2)-2-(l-trimethylsilyl-l-hexenyl)dibromo-borane is observed during the hydrolysis followed by treatment with 1,3-propanediol. 

Treatment of an epimeric mixture of 4-substituted 2-(trimethylsilyloxy)-5-phenyl-3-phenylthio-l,4-oxazine 264 with ZnBr2 led to the stereoselective formation of perhydropyrido[2,l-c][l,4]oxazine 266 via the iminium ion 265 by the phenyl bearing stereocenter directed addition of the olefinic double bond from the /S-face of the cyclic moiety (97SL799, 98T10309). Similarly, an epimeric mixture of (45,9aS)-l-trimethylsilyloxy-4-phenyl-3,4,6,7-tetra-hydropyrido[2,l-c][l,4]oxazine was prepared by cyclization of (Z)-5(S)-phenyl-3-phenvlsulfanyl-2-trimethylsilyloxy-4-[4-(trimethylsilyl)but-3-enyll morpholine (OOSC2565). 

R = C6H5 3-XerX-hutyldimeth lsilyloxv-2-methoxymethoxy-i-phenyl-l-trimethylsilyl-t-hutanoll0i yield 86% d.r. [(1R,2S,3R)/(1S,2S,3R)] 98 2... 

Freparatively useful induced diastereoselectivities have been reported mainly for 1,1-di-substituted allyllithium derivatives which bear carbanion-stabilizing substituents. l-[Methyl-thio-l-(trimethylsilyl)-2-propenyl]lithium106 and the appropriate 1-phenylthio107 derivative, generated from the allylic sulfide with sec-butyllithium, in the reaction with tetrahydropyranyl-protected pregnolone, furnish a single diastereomer. 

Tetramethyl-2-(3-trimethylsilyl-2-propenyl)-l,3,2-dioxaborolane Typical Procedure2 11 ... 

The silicon- and sulfur-substituted 9-allyl-9-borabicyclo[3.3.1]nonane 2 is similarly prepared via the hydroboration of l-phenylthio-l-trimethylsilyl-l,2-propadiene with 9-borabicy-clo[3.3.1]nonane36. The stereochemistry indicated for the allylborane is most likely the result of thermodynamic control, since this reagent should be unstable with respect to reversible 1,3-borotropic shifts. Products of the reactions of 2 and aldehydes are easily converted inlo 2-phenylthio-l,3-butadienes via acid- or base-catalyzed Peterson eliminations. 

In a second set of examples, it was shown that the stereoselectivity of the aldehyde allylborations of 9-[( T)-l-trimethylsilyl- or l-trimethylstannyl-2-butenyl]-9-borabicyclo[3.3.1]nonane is controlled to a significant extent by conversion to an ate complex by treatment with butyllithium, MT-butyllithium or pyridine19. 

R = C6H5 (3S,4R)-3-[(R)-t-(4-nitrophenylmethoxycarbonyloxy)ethyl -4-(phenyhhiocarbonylmethyl)-l-trimethylsilyl-2-azetidinone 05 yield 93%... 

A solution of ( )-l,2-bis(trimethylsilyl)oct-l-ene (12mmol) in glacial AcOH (31 ml) and H20 (1.6 ml) was heated with stirring at 110°C for 29 h. The mixture was then cooled to0°C, aqueous NaOH (60 ml, 9 m) added, and the total was extracted with ether (50 ml). The ethereal extract was washed with saturated sodium hydrogen carbonate solution and brine, and dried. Concentration and distillation gave 2-trimethylsilyloct-l-ene (U.5mmol, 96%), b.p. 106 °C/1 mmHg. 

A solution of TMSOTf in dichloromethane (1% v/v, 1 ml) was added to a solution of the /3-lactam (2.01 mmol) and 1-phenyl-l-trimethylsilyl-oxyethene (2.2 mmol) in dichloromethane, cooled to -78°C. After being stirred at -78°C for 15 min, the reaction mixture was allowed to warm to ambient temperature over 20 min, and was stirred for a further 30 min. The lime-green solution was quenched with aqueous K.F (5% w/v, 20ml) and extracted with dichloromethane (2x25 ml). Drying, concentration and chromatography of the residue gave the -lactam (1.79 mmol, 89%) as a white solid, m.p. 141-143"C. 

C6H7NO3S2 138890-97-8) see Brinzolamide dihydro-2-imino-5-methoxy-4,6(1/1,5/I)-pyrimidinedione (C,H7N,0, 89280-05-7) see Sulfametoxydiazine 23-dihydro-2-(l-iminopropyl)-2-[(trimethylsilyl)oxy ]- //-indene... 

The diacetal 629, prepared from the carbonyl compound and O-silylated allylic alcohols in the presence of TMSOTf 20, reacts with ( )-l-trimethylsilyl-2,4-penta-diene 630, in the presence of TMSOTf 20 in CH2CI2 at -78°C, to afford 60% 631 this undergoes Diels-Alder-cyclization at 170 °C in toluene to give a substituted... 

Analogously, the silylated / -hydroxyallylsilane 655 condenses with excess dihy-drocinnamaldehyde in the presence of TMSOTf 20 at -78 °C to afford, via 656, the dihydropyran 657 in 82% yield [191] (Scheme 5.58). Condensation of benzaldehyde with methoxytrimethylsilane 13 a and l-trimethylsilyl-2-butyne 658 in the presence of TMSOTf 20 in CH2CI2 affords the allenyl compound 659 in 97% yield and HMDSO 7 [192]. 

Hydroxy(tosyloxy)iodobenzene 2014 reacts with phenyltrimethylsilane 81 in boiling acetonitrile to give diphenyliodonium tosylate 2015 and trimethylsilanol 4 or HMDSO 7 [184, 185]. Likewise, treatment of 2,5-bis(trimethylsilyl)furan 2016 with 2014 in boiling acetonitrile/methanol affords 78% iodonium tosylate 2017 and trimethylsilanol 4 [185]. In the presence of Bp3-OEt2 iodosobenzene oxidizes allyl-trimethylsilanes such as 2018 to unsaturated aldehydes such as 2019 in 63% yield, with formation of iodobenzene and trimethylsilanol 4 [186]. Analogously, vinyltrimethylsilanes such as (Z)-l-trimethylsilyl-2-phenylethylene 2020 afford, via 2021, acetylenes such as phenylacetylene in 61% yield and iodobenzene and trimethylsilanol 4 [187] (Scheme 12.54). 

---