Antony Bigot

Reductive deprotection of aryl allyl ethers with Pd(Ph3)4/NaBH4

Treatment of aryl allyl ethers with catalytic amts. of Pd(PPh3)4 and NaBH4 at room temp. afforded the parent phenol in high yield under non-hydrolytic conditions. E.g., treatment of ether I (R = allyl) with NaBH4 in the presence of Pd(PPh3)4 in THF gave 97% I (R = H). [on SciFinder (R)]

A novel synthesis of K-13

A new and concise synthesis of the 17-membered macrocyclic tripeptide K-13 is achieved featuring an intramol. SNAr reaction as a key step. [on SciFinder (R)]

An easy access to functionalized diaryl ethers: formal total synthesis of K-13

As an alternative to the Ullmann ether synthesis, the SNAr reaction led to an efficient one step synthesis of chiral bis-amino acid diaryl ethers, e.g. the reaction of 2-FC6H4NO2 with tyrosine deriv. Boc-Tyr-OMe in the presence of base gave diaryl ether I. The above diaryl ethers are important intermediates in the synthesis of K-13 II. [on SciFinder (R)]

4-Nitrophenyltriflate as a new triflating agent

Aryl triflates were prepd. under mild conditions using 4-nitrophenyl triflate as a stable, cryst. triflating agent. [on SciFinder (R)]

A concise and efficient synthesis of protected actinoidic acid, the degradation product of vancomycin

Protected actinoidic acid I, one of the degrdn. products of vancomycin, has been efficiently synthesized by a convergent route which is amenable to large scale application as well as to asym. synthesis. [on SciFinder (R)]

An efficient total synthesis of K-13, a non-competitive inhibitor of ACE I

An efficient synthesis of K-13 (I), a non-competitive inhibitor of ACE I with an endo biaryl ether bond, is described. The key cycloetherification reaction of linear tripeptide II gave a 17-membered macrocycle in quant. yield. [on SciFinder (R)]

A FORMAL TOTAL SYNTHESIS OF DEOXYBOUVARDIN

A synthesis of L,L-N,N-dimethylcycloisodityrosine (I) based on an intramol. SNAr reaction is reported. A possible explanation was proposed to account for the facile epimerization encountered in the cycloetherification of dipeptide L,L-II and a soln. to this problem led to a formal total synthesis of deoxybouvardin. [on SciFinder (R)]

Synthesis of cycloisodityrosine revisited: A selective ring forming process

An efficient synthesis of cycloisodityrosine was developed based on an intramol. nucleophilic arom. substitution reaction for the selective ring formation of a key biaryl ether intermediate. Cycloetherification of dipeptide I gave exclusively the (meta,para)-cyclophane II (R = OH, R1 = NO2, R2 = Me3CO2C, R3 = H) at the expense of the 15-membered (para,para)-cyclophane III as a result of an enthalpy controlled process. The (meta,para)-cyclophane II (R = OH, R1 = NO2, R2 = Me3CO2C, R3 = H) was easily transformed to N,N-dimethyl cycloisodityrosine II (R = OMe, R1 = H, R2 = Me, R3 = Me), an important structural subunit of bouvardin and the RA series. [on SciFinder (R)]