Ring syntheses

The last decade has witnessed the growing use of olehn metathesis in organic synthesis.Ring closing metathesis RCM, Eq. (6)] and ring opening metathesis [ROM, Eq. (7)1 as well as a combination of these transformations have resulted in providing opportunities to build molecules of interest and importance. 

Medium sized carbocycle synthesis Ring contracting [1,2]-Wittig rearrangement Yadav and Ravishankar have demonstrated that the Wittig rearrangement of the cyclic substrate 32 is useful for the construction of the taxane skeleton 33, albeit in low yield (equation 17). ... 

Moore, J. S. Transition Metals in Polymer Synthesis Ring-opening Metathesis Polymerization and Other Transition Metal Polymerization Techniques. In Comprehensive Organometaltic Chemistry // Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Elsevier Oxford, 1995 Vol. 12, pp 1209-1232. 

Lipase Transesterification and direct esterification (inch polyester synthesis) Ring-opening polymerization of 8-caprolactone Hydrolysis alcoholysis acetylation Higher stability of enzyme greater activity catalyst recyclable sometimes higher enantio- and regio-selectivity compared with VOCs... 

WASSERMANN - BORMANN Macrecydic lactam synthesis Ring expansion sequence o< lactams by reaction wRh cycfc bninoetheis (OSowed by reductive ring opening to a macrocydic lactam. 

Y. Nakagawa, G.S. Lee, T.V. Harris, L.T. Yuen, and S.I. Zones, Guest/host Relationships in Zeolite Synthesis Ring-substituted Piperidines and the Remarkable Adamantane Mimicry by 1-Azonio Spiro[5.5]undecanes. Microporous Mesoporous Mater., 1998, 22, 69-85. 

Sodium salt of 12-tungstophosphoric acid acts as catalyst for isomerization, polymerization, nitrile synthesis, dehydrochlorination, dehydrogenation, ketone synthesis, ring-closure synthesis, oil bodying, aromatization, and desulfurization [10.4,10.21]. 

WASSERMANN - BOR MANN Macrecycfc lactam synthesis Ring expansion sequence of lactams by reaction with cycfc kninoethers followed by reductive ring opening to a macrocyclie lactam. 

SYNTHESIS Ring-opening polymerization of cyclooctene in the presence of Ziegler-Natta catalysts. 

SYNTHESIS Ring-opening polymerization of cyclopentene. Trflns-jxrlypentenamer is produced by Ziegler-Natta polymerization employing a catalyst based on aluminum triethyl/tungsten hexachloride compound. Aluminum diethylchloride/ molybdenum pentachloride compounds may be employed to produce the as isomer. Both macrocycles and linear chains are produced during polymerization. 

Scheme 3. New directions in organic synthesis ring-closing metathesis as a key step in Nicolaou s total synthesis of coleophomones C and B (46 and 47).

Gurjar and co-workers prepared several novel carbohydrate-based spirocycles and a spirocyclic proline derivative for applications in peptide, nucleoside, and carbohydrate synthesis. Ring-closing metathesis of carbohydrate diene precursor 78 furnished the corresponding spirocycle 80 in 88% yield using a catalytic amount of 3 in dichloromethane. Reaction of proline derivative 79 under similar conditions gave the corresponding spirocyclic peptide 81 in 96% yield. 

POLYPEPTIDE SYNTHESIS, RING-OPENING POLYMERIZATION OF a-AMINO ACID yV-CARBOXYANHYDRIDES... 

Method of synthesis ring-opening addition polymerization of 8-caprolactone at 170°C under nitrogen with dibutyl stanneous oxide as the catalyst also condensation of 6-hydroxycaproic acid gives PCL polymerization is frequently conducted in extruder Kim, B J White, J L, Antec, 224-8, 2000 Label, M Thielemans, Chem. Soc. Rev., 38,3484-3504, 2009. 

Method of synthesis - ring opening methathesis polymerization of dioyolopentadiene ... 

Method of synthesis ring-opening polymerization of p-dioxanone in the presence of organometallic catalyst (e.g., zirconium acetylacetone) Li, Y Whng, X-L, Yang, K-K Wang, Y-Z, Polym. Bull., 57,873-880, 2006. 

Mannich synthesis, — ring opening, — Decomposition, thermal... 

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