Diana S. Stoianova

Ring closing metathesis reactions on a phosphonate template

The first examples of ring-closing metathesis reactions on a phosphonate template catalyzed by the ruthenium alkylidene 3 are described. The yield, rate, and mode of cyclization in these reactions are sensitive to simple olefin substitution. The highlight of this method is the efficient syntheses of 2-alkyloxy-3,6-dihydro-[1,2]oxaphosphinine 2-oxide heterocycles (2).

RING-CLOSING METATHESIS STRATEGY TO P-HETEROCYCLES

The first examples of ring-closing metathesis reactions with allylphosphonamides1, vinylphosphonamides2, and vinylphosphonates8 using the Grubbs ruthenium catalyst3 are described. These RCM reactions lead to the 6-membered allylphosphonamides4, the 5-membered vinylphosphonamides5, and various 5-, 6- and 7-membered phosphonates9–10. The yield, rate and mode of metathesis in these reactions are sensitive to simple olefin and nitrogen substitution. The first examples of ring-closing metathesis reactions with allylphosphonamides1, vinylphosphonamides2, and vinylphosphonates using the Grubbs ruthenium catalyst3 are described. These RCM reactions lead to 6-membered allylphosphonamides4, 5-membered vinylphosphonamides5, and various 5–7 membered cyclic phosphonates. The yield, rate and mode of metathesis are sensitive to simple olefin and nitrogen substitution. Download full-size image

Silica-Supported Oligomeric Benzyl Phosphate (Si-OBP) and Triazole Phosphate (Si-OTP) Alkylating Reagents

The syntheses of silica-supported oligomeric benzyl phosphates (Si-OBP(n)) and triazole phosphates (Si-OTP(n)) using ring-opening metathesis polymerization (ROMP) for use as efficient alkylating reagents is reported. Ease of synthesis and grafting onto the surface of norbornenyl-tagged (Nb-tagged) silica particles has been demonstrated for benzyl phosphate and triazole phosphate monomers. It is shown that these silica polymer hybrid reagents, Si-OBP(n) and Si-OTP(n), can be used to carry out alkylation reactions with an array of different nucleophiles to afford the corresponding benzylated and (triazolyl)methylated products in good yield and high purity.

Development and Application of a Recyclable High-Load Magnetic Co/C Hybrid ROMP-Derived Benzenesulfonyl Chloride Reagent and Utility of Corresponding Analogues

The development and application of high-load, recyclable magnetic Co/C hybrid ROMP-derived benzenesulfonyl chloride and analogues is reported. The regeneration and utility of these reagents in the methylation/alkylation of various carboxylic acids is demonstrated via efficient retrieval of the magnetic reagent with a neodymium magnet. Additional reactions employing the analogue sulfonic acid and in situ generated magnetic benzenesulfonyl azide are also reported.

Ring-Closing Metathesis Approach toward Phosphonosugars

The ring closing metathesis (RCM) reaction continues to emerge as a powerful approach for the construction of complex organic molecules.1−3 Recently we have shown that the RCM reaction catalyzed by the Grubbs ruthenium catalyst is an effective method for the construction of phosphonate P-heterocycles.4 As a part of our program aimed at developing organometallic approaches to diverse phosphorus containing compounds, we herein report our efforts toward synthesis of cyclic phosphonate (phostones) analogs of carbohydrates containing phosphorus atom at the anomeric position. This class of compounds has received continued attention in the literature.5 Previous routes to phostone sugar analogs have employed the Abramov reaction of sugar aldehydes and dior trialkyl phosphites, followed by intramolecular transesterification of the resulting hydroxyphosphonates. Our strategy utilizes the RCM reaction for the formation of the six-membered cyclic allylic phosphonates 4, 5. Epoxidation or dihydroxylation of these compounds followed by opening of the epoxide or cyclic carbonate results in the formation of a vinylphosphonates containing a hydroxy group at

Ring Closing Metathesis Reactions on Phosphonamide and Phosphonate Templates

Abstract Phosphonrs containing organic compounds have shown enormous potential in the development of novel pharmaceutical and agricultural agents [1,2]. One attractive route into the formation of complex phosphonamides and phosphonates is via the RCM reaction of acyclic substrates such as 1,4. and 6. Recently we published the first example of a RCM reaction on a phosphonate template [4]. Although the RCM reaction has emerged as a powerful tool in the synthesis of complex ring systems [3]. only one other example exists in the literature of a RCM reaction on phosphines using a tungsten carbene catalyst [5]. As part of our program aimed at developing organometallic approaches to diverse phosphorus containing compounds, we herein report the first examples of RCM reactions on phosphonamide templates such as 1 and 4 using the ruthenium catalyst 2. In addition. we report new examples of RCM reactions on phosphonate templates such as 6.

Diastereotopic Differentiation to P -Chiral Phosphonamides and Phosphonates

As part of our program aimed at developing transition metal-catalyzed approaches to diverse phosphorus-containing compounds, we herein report examples of utilizing the ring-closing metathesis reaction (RCM) in the diastereotopic differentiation of pseudo-C2-symmetric phosphonamide and phosphonate templates generating P-heterocycles 1 and 2. The RCM reaction continues to emerge as a powerful approach for the construction of complex organic molecules. Recently we have shown that the RCM reaction catalyzed by the Grubbs ruthenium catalyst is an effective method for the construction of phosphonate and phosphonamide P-heterocycles.1−3