Stereochemistry of Asymmetric Silicon. II. Alkoxy and Siloxy Leaving Groups

Sommer, L. H.; Frye, C. L.; Parker, G. A.

doi:10.1021/ja01070a015

Cited by 48 publications

(29 citation statements)

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“…Oxobis[triphenylsilicon(IV)] was prepared by a method analogous to that used for the preparation of oxobisl~-naphthylphenylmethylsilicon (IV)] (Sommer, Frye & Parker, 1964).…”

Section: Experimental Preparationmentioning

confidence: 99%

The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

Glidewell¹,

Liles²

1978

Acta Crystallogr Sect B

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Crystals of oxobis(triphenylsilicon), O(SiPh3)2, are triclinic, space group P|, a = 11.301 (2), b = 9-539 (2), c = 8.771 (2) A, tt = 66.34 (1), fl = 114.35 (I), y = 114.24 (1) °, Z = 1. The structure was solved by direct methods using diffractometer data and refined by full-matrix least squares to R = 0.0374. The molecules are centrosymmetric, so that the SiOSi fragment is strictly linear: principal interatomic distances are Si-O 1.616 (1) A, and Si-C 1.864 (5) A; the central C6Si20 part of the molecule exhibits almost exact 3m symmetry.

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“…Oxobis[triphenylsilicon(IV)] was prepared by a method analogous to that used for the preparation of oxobisl~-naphthylphenylmethylsilicon (IV)] (Sommer, Frye & Parker, 1964).…”

Section: Experimental Preparationmentioning

confidence: 99%

The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

Glidewell¹,

Liles²

1978

Acta Crystallogr Sect B

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“…Moreover, we devised a novel concept for the non-enzymatic kinetic resolution of chiral secondary alcohols employing asymmetrically substituted silanes as recyclable resolving agents. [7] A rationale for the notorious track record of failure [4] is probably provided by the structure of standard silane (SiR)-1 [8] (Figure 1), which illustrates the pivotal features intrinsically connected with asymmet- FULL PAPERS rically substituted silanes: [4] (1) relatively long carbon-silicon bonds thwarting compact stereochemistry-determining transition states and (2) insufficient stereochemical differentiation at silicon. In order to create more conformational rigidity as a measure against the detrimental carbon-silicon bond length, the silicon center might be embedded into a cyclic framework [(SiS)-2 [9] and (SiR)-3/A C H T U N G T R E N N U N G (SiS)-3,…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10]12] For this purpose, rac-A is optionally transformed into the corresponding chloro-or alkoxysilane followed by reaction or transetherification with D. After separation of diastereomers G and epi-G, which is usually achieved by classical techniques (fractional crystallization and chromatography), the ethers G and epi-G are individually converted into enantiopure A and ent-A, respectively by reduction without racemization at silicon (vide infra).…”

Section: Introductionmentioning

confidence: 99%

Preparation of a Privileged Silicon‐Stereogenic Silane: Classical versus Kinetic Resolution

Rendler¹,

Auer²,

Keller³

et al. 2006

Adv Synth Catal

101

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Abstract:The cyclic silicon-stereogenic silane (SiR)-5 decorated with three different substituents of distinct steric demand is an exceptionally useful chiral reagent in asymmetric organosilicon chemistry. Several approaches for its large-scale preparation in optically pure form have been investigated. These hinge upon the resolution of racemic silane rac-5 which, in turn, is accessible in multi-gram quantities by a straightforward one-pot two-step reaction sequence. For this, a classical as well as a novel kinetic resolution via its diastereomeric silyl ethers derived from enantiopure secondary alcohols as resolving agents has been elaborated: (1) the use of (À)-menthol [(À)-7] allowed for a quantitative separation of silyl ethers (SiS)-10 and (SiR)-10 by practical fractional crystallization and (2) a diastereoselective copper-catalyzed dehydrogenative silicon-oxygen coupling using pyridyl alcohols (S)-16 or (R)-16 capable of two-point binding has been devised and assessed as a novel kinetic resolution strategy for the synthesis of a silane with silicon-centered chirality. Subsequent stereospecific reductive cleavage of the silicon-oxygen bond enabled the preparation of (SiR)-5 and (SiS)-5 in excellent enantiomeric excesses of up to 99 % ee.

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“…The stereospecificity of the reactions in Scheme 2 is vitally important for obtaining the bifunctional vinyl-hydro-disiloxane monomer with high optical purity. According to Sommer et al, [15] reactions of optically active methyl(1-naphthyl)phenylalkoxysilane with KOH proceeded with high stereospecificity. Every step in the synthesis is confirmed to be highly stereospecific.…”

Section: Resultsmentioning

confidence: 99%

Stereoregular silicon‐containing polymers

Kawakami

2001

Polymers for Advanced Techs

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Optically active (R)-methylphenylpropargylsilane and (S)-2-(1-naphthyl)-2-phenyl-5,5-dimethyl-1-oxa-2,5disilacyclopentane were prepared, and stereoregular and optically active polymers were obtained via hydrosilylation or ring-opening polymerization. Both polymerization reactions proceeded stereoselectively, and the tacticity of the polymers reflected the optical purity of the monomers. / KawakamiFIGURE 3. 1 H-NMR spectra of poly[(R)-4b]. (a) Oligomers from rac-4b by [Rh(COD) 2 ]BF 4 /2PPh 3 ; (b) poly[(R)-4b] from (R)-4b by PtDVTMDS; (c) poly[rac-4b] from rac-4b by PtDVTMDS.FIGURE 4. (a) 1 H-, (b) 13 C-and (c) 29 Si-NMR spectra of poly[(S)-7]. Stereoregular Silicon-containing Polymers / 661 FIGURE 7. 29 Si-NMR spectra of (a) model compounds by the reaction of 8 and initiator in a ratio of 1 : 1 and (b) poly(8).

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Stereochemistry of Asymmetric Silicon. II. Alkoxy and Siloxy Leaving Groups

Cited by 48 publications

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The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

Preparation of a Privileged Silicon‐Stereogenic Silane: Classical versus Kinetic Resolution

Stereoregular silicon‐containing polymers

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Stereochemistry of Asymmetric Silicon. II. Alkoxy and Siloxy Leaving Groups

Cited by 48 publications

References 0 publications

The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

Preparation of a Privileged Silicon‐Stereogenic Silane: Classical versus Kinetic Resolution

Stereoregular silicon‐containing ­polymers

Contact Info

Product

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Stereoregular silicon‐containing polymers