A. Sanjeev Kumar

A short and efficient synthesis of valsartan via a Negishi reaction

Summary An efficient synthesis of the angiotensin-II inhibitor valsartan (Diovan®) is presented. Directed ortho-metalation of 5-phenyl-1-trityl-1H-tetrazole (6) and its Negishi coupling with aryl bromide 5 are the key steps of the synthesis. This method overcomes many of the drawbacks associated with previously reported syntheses.

Efficient and improved synthesis of Telmisartan.

Summary An efficient synthesis of the angiotensin II receptor antagonist Telmisartan (1) is presented involving a cross coupling of 4-formylphenylboronic acid 10 with 2-(2-bromophenyl)-4,4-dimethyl-2-oxazoline (11) as the key step (90% yield). The benzimidazole moiety 15 was constructed regioselectively via a reductive amination-condensation sequence, replacing the alkylation of the preformed benzimidazole step in the previously published route. This methodology overcomes many of drawbacks associated with previously reported syntheses.

New and Improved Synthesis of Telmisartan: An Antihypertensive Drug

Abstract An improved, cost-effective, and industrially advantageous process suitable for large-scale production of telmisartan 1 has been described. The key steps include Suzuki coupling for the preparation of key intermediate 2-(4′-chloromethyl-biphenyl-2-yl)-4,4-dimethyl-4,5-dihydrooxazole 10 of telmisartan, N-alkylation, and oxazoline hydrolysis.

Convenient synthesis of Valsartan via a Suzuki reaction

An efficient synthesis of the angiotensin II inhibitor Valsartan (Diovan) is presented. The formation of the aryl–aryl bond represents the key step of its synthesis, which has been done by a Suzuki coupling of aryl boronate with 2-bromophenyl oxazoline with good yield and purity. This method overcomes many of the drawbacks associated with the previously reported syntheses.

Improved Synthesis of Valsartan via Nucleophilic Aromatic Substitution on Aryloxazoline

Abstract A highly efficient approach to the synthesis of the angiotensin II receptor antagonist valsartan (Diovan), one of the most important agents used in antihypertensive therapy today is described. The formation of the aryl–aryl bond represents the key step of its synthesis, which has been done by simple nucleophelic aromatic substitution on aryloxazoline with good yield and purity.

A modification to the synthesis of Telmisartan: an antihypertensive drug

A highly efficient approach to the synthesis of Telmisartan is described. Directed ortho-metalation of 4,4-dimethyl-2-phenyl-4,5-dihydrooxazole provided the key organozinc intermediate for a palladium catalysed biaryl coupling with 3′-(4-bromobenzyl)-1,7′-dimethyl-2′-propyl-1H,3′H-2,5′-bibenzo[d]imidazole which was obtained from alkylation of 1,7′-dimethyl-2′-propyl-1H,3′H-2,5′-bibenzo[d]imidazole. This methodology overcomes many of the drawbacks associated with previously reported syntheses.

Convenient synthesis of amaryllidaceae alkaloid, (+/–) latifine dimethyl ether

A short route for the synthesis of (+/-) latifine dimethyl ether is reported. The key steps involved are Grignard reaction, conversion of alcohol to nitrile using trimethylsilyl cyanide, reduction of the nitrile intermediate followed by Pictet–Spengler cyclisation and reductive N-methylation in a single step to provide latifine dimethyl ether as a racemate.

An efficient synthesis of (+/-) cherylline dimethyl ether

A concise route for the synthesis of (+/-) cherylline dimethyl ether is reported. The key steps involved are Grignard reaction, conversion of alcohol to nitrile using (N-(p-toluene sulfonyl)imidazole and sodium cyanide), reduction of the nitrile intermediate followed by Pictet–Spengler cyclisation and reductive N-methylation in a single step to provide cherylline dimethyl ether as a racemate.

New strategy for the synthesis of (+/-) latifine and cherylline dimethyl ether

A concise route for the synthesis of (+/-)-latifine and (+/-)-cherylline dimethyl ethers is reported. The key steps involved are the Michael type addition of p-methoxybenzene magnesium bromide to the (E)-1,2-dimethoxy-3-(2-nitrovinyl)benzene, reduction of the nitro intermediate obtained followed by the Pictet-Spengler cyclization and reductive N-methylation.