silyl protecting groups

Larger substituents increase resistance to hydrolysis, but also make introduction of the silyl group more difficult. Silyl groups can conveniently be used as protection for an imine nitrogen. Chem.

Figure 54. There are several hotly contested theories so there is no “right” answer. Compound TMSPC(But)OTMS was converted into the liquid phosphaalkene 52 by the reaction with hexafluoroacetone in THF <1995CB499>. Extremely hindered allylsilanes have been noted to react without allylic rearrangement (equation 16),64 and steric arguments may account for acylations that take place with apparent overall syn addition (equation 17).65. It should be noted that the large range of available silyl ethers display a large range of sensitivity to acid and base (too large to go into here!) There are many other tri-alkyl-silyl-chloride reagents besides TMSCl which are far more bulky. Silyl ethers will be cleaved by nucleophiles (especially oxygen and fluoride) to form Si-O/F bonds – F– is therefore particularly effective because it is small and generally unreactive.

-Serving as effective protective groups for alcohols, silyl ethers are used extensively in laboratory scale synthesis. Home  |  Contact  |  About  |  Amazon Disclaimer  |  Terms and Conditions  |  Privacy Policy  |  Legal Disclaimer  |  Sitemap. The potassium salt of the same aza-allyl underwent oxidative coupling to give meso-bisimine 109 in high yield (Equation (42)) <1997JOM(549)1>. Silyl protecting groups These silicon based protecting groups form through the formation of an silyl ether. For instance, reaction of cinnamaldehyde with the lithium amide derived from compound 102 gave imine 103 in extremely high yields (Equation (39)) <1997S886, 1998TL6257>.

Stephen C. Eyley, in Comprehensive Organic Synthesis, 1991. Incorporation of heteroatomic or functionalized substituents into the starting α,α-bis(silyl)carbanion allows for the synthesis of the corresponding substituted alkenylsilanes <76TL4041, 77CB852, 93SL863>. The latter is more reactive and suited to the protection of secondary and tertiary alcohols. Chlorination by hexachloroethane furnished the isolable species (26) (65%), which is further converted into (27) by an excess of (25) (75%) <83CB938>, whereas treatment of (25) with an excess of neat pivaloyl chloride at 70–80 °C gave compound (28) in 68% yield (Scheme 9) <77ZAAC(430)66>. Mechanism proposed for the Rh-catalyzed conversion 2-(trimethylsilyl)-phenylboronic acid and internal alkynes to silaindenes.22. In one case, the reaction involved a pyridine-tethered diyne where the product is a 5-silaindeno[3,2-b]pyridine, 2–13, as shown in Equation (14) and in Table 2. Lothar Weber, in Comprehensive Organic Functional Group Transformations, 1995. Sorry, your blog cannot share posts by email. Change ), Protecting groups in carbohydrate chemistry, Carbohydrate synthesis with organocatalysis. N-Silyl bisimines such as 100 are readily accessed by this method (Equation (38)) <1999TL8523, 1999HAC423>. -At least two of the three R’ groups are the same group, because if all three were different the silicon atom would be stereogenic and could give rise to diastereomers, which would complicate handling of the compound.

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