Hydroxyselenylation and Tethered Silanoxyselenylation of Allylic Silanols

Abstract

We present protocols for the highly regioselective hydroxyselenylation and silanoxyselenylation of allylic silanols. N-(Phenylseleno)­phthalimide acts as the selenylating agent for both transformations. Under basic conditions, hydroxyselenylation proceeds with >20:1 regioselectivity, and the products are valuable synthons for further transformations. We show that the silanol plays a critical role in maintaining the yield and regioselectivity of this reaction. Surprisingly, under acidic conditions, the hydroxyselenylation pathway is blocked, and products of a tethered silanoxyselenylation are exclusive.

Covalent Tethers for Precise Amino Alcohol Syntheses: Ring Opening of Epoxides by Pendant Sulfamates and Sulfamides

“…The precise construction of polyfunctional molecules remains a topic of great interest. , Many targets of value are densely functionalized and comprise several contiguous stereocenters. The ring opening of epoxides is an attractive method for the assembly of alcohol-containing stereoarrays. − Our laboratory has a programmatic focus on the use of unusual nucleophiles for the ring opening of both transient − and stable electrophiles. , As part of this line of inquiry, it occurred to us that a ring opening of epoxides by pendant sulfamates and sulfamides would offer predictable access to vicinal amino alcohols and would complement our previous efforts with intramolecular cleavage of aziridines by di- tert -butylsilanol auxiliaries …”

Unusual Covalent Tethers for Precise Amino-Alcohol Syntheses: Ring Opening of Epoxides by Pendant Sulfamates and Sulfamides

“…The ring-opening of epoxides is an attractive method for the assembly of alcohol-containing stereoarrays. [3][4][5][6][7] Our laboratory has a programmatic focus on the use of unusual nucleophiles for the ring-opening of both transient [8][9][10][11][12][13] and stable electrophiles. 14,15 As part of this line of inquiry, it occurred to us that a ring-opening of epoxides by pendant sulfamates and sulfamides would offer predictable access to vicinal amino-alcohols and would complement our previous efforts with intramolecular cleavage of aziridines by di-tert-butyl-silanol auxiliaries.…”

Ring Opening of Aziridines by Pendant Silanols Allows for Preparations of (±)-Clavaminol H, (±)-Des-Acetyl-Clavaminol H, (±)-Dihydrosphingosine, and (±)-N-Hexanoyldihydrosphingosine

“…Temporary tethering using Lewis acid templates affords excellent regiocontrol with epoxides, − but only one such report exists with aziridines . Our laboratory has a programmatic focus on the development of the di- tert -butyl-silanol auxiliary into a uniquely reactive functional handle. − We envisioned a ring opening of aziridines by pendant di- tert -butyl silanol auxiliaries, which would afford protected amino alcohols in a single transformation. Here, we show our development of this reaction, and its application in the rapid assembly of select natural products and analogues.…”