A convenient and mild protocol for preparation of α –trimethylsilyloxyphosphonates using sulfamic acid and their oxidation to α – ketophosphonates in the presence of N-bromosuccinimide

Satish D Mitragotri,Prakash P Wadagaonkar,Makarand A Kulkarni,Uday V Desai

doi:10.24820/ark.5550190.p011.603

Satish D Mitragotri, Prakash P Wadagaonkar + Show 2 more

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https://doi.org/10.24820/ark.5550190.p011.603

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Abstract

A convenient and mild protocol for preparation of α –trimethylsilyloxyphosphonates using sulfamic acid and their oxidation to α – ketophosphonates in the presence of N-bromosuccinimide

Highlights

The major driving force for development of new methodologies in organic synthesis stems from the need to achieve targeted transformations in a convenient and an efficient manner
As a part of research programme in our laboratory on utilization of solid acid catalysts in organic transformations in general,19,20 and investigations pertaining to sulfamic acid (SA)[21,22,23,24,25,26,27,28,29,30,31,32,33] in particular, we planned to test the utility of SA as a protic acid catalyst for silylation of α- hydroxyphosphonates using hexamethyldisilazane (HMDS) as the silylating agent to obtain α-trimethylsilyloxyphosphonates as well as a catalyst for their deprotection to regenerate parent α– hydroxyphosphonates (Scheme 1)
Stirring together a mixture of α-hydroxyphosphonate (2 mmol), HMDS (1.6 mmol), dichloromethane (5 ml) and SA (30 mg, 15 mol %) at room temperature resulted in the formation of corresponding α-trimethylsilyloxyphosphonate as the sole product (TLC)

Summary

Introduction

The major driving force for development of new methodologies in organic synthesis stems from the need to achieve targeted transformations in a convenient and an efficient manner. Stirring together a mixture of α-hydroxyphosphonate (2 mmol), HMDS (1.6 mmol), dichloromethane (5 ml) and SA (30 mg, 15 mol %) at room temperature resulted in the formation of corresponding α-trimethylsilyloxyphosphonate as the sole product (TLC). 91 25 2.0 84 34 a: α- Hydroxyphosphonate (2 mmol ), HMDS (1.6 mmol), SA (15 mol %), dichloromethane (5 mL), RT ; b: α- Trimethyl-silyloxyphosphonate (2 mmol ), SA (15 mol %), methanol (5 mL), RT ; c: αTrimethylsilyioxyphosphonate (2 mmol ), NBS (2 mmol), AIBN (15 mg),carbontetrachloride (5 mL), RT; d: Yields refer to isolated pure products, e : not reported in the literature

Results

Conclusion