Secondary ring

It can be seen that the set of synthetically significant rings include the "primary rings" I, 2, 3, 4 and the "secondary rings" 5 and 6. 

Symmetrical differences secondary rings, core bonds and bridgeheads ... 

Preuent if intramolecular l-l Preuent reconnections in rings <= 7 members and in secondary rings... 

In the disconnection tables, when we refer to "prevention against strained system", we mean that "prevents reconnection to rings of less than 8 members and secondary rings". 

Ethylindane, and 2-methylnaphthalene (the latter being the product of secondary ring contraction of benzcycloheptane). 

Pyran 85b readily gave with various primary amines RNH2 at room temperature ring-opened products formulated as 506.62 If hydrazine hydrochloride or A,A -dimethylhydrazine and perchloric acid were used instead of the amines, the ring opening was accompanied by a secondary ring closure to lead to bispyrazolyl derivatives 507 or 508, respectively.418... 

Most naturally occurring nucleosides and nucleotides contain a ribofuranose moiety, From detailed 13C NMR studies of carbohydrates [88, 89, 696] it is known that primary CH2OH groups resonate at higher field than the secondary ring CHOH groups, and thus... 

The secondary ring carbon atoms are preferentially oxidized with respect to that of the methyl group. A simple statistical calculation demonstrates that they are 6.5 times more Teactive. This behaviour is opposite to the gas phase photocatalytic oxidation of toluene (ref. 4), which produces only traces of benzaldehyde, whereas the aromatic ring withstands oxidation, at least in pure gas or liquid organic phase and in the absence of water. The above selectivities seem to be correlated to steric factors governing the mode of adsorption of methylcyclohexane on the surface of titania. 

The study revealed that CAL-A is an efficient biocatalyst in the highly (Y)-selective acylation at the secondary ring nitrogen of methyl pipecolinate 69. The unreacted (R)-69 was recovered with an ee up to 95% and the product (,S)-69 with >99 % ee with an E... 

In the case of furfurylidene ketones, a furan is again formed, as the result of a secondary ring closure206 ... 

The reactivity of epoxy groups towards nucleophilic and electrophilic species can be explained through the release of ring strain in the three member oxirane group. Nucleophilic curatives such as amines or mercaptans attack the secondary ring carbon while electrophilic curatives behave as Lewis or Bronsted acids. The epoxy ring can be opened by hydroxyl or other epoxy group aided by tertiary amines, Lewis acids or coreactants such as primary amines, mercaptans and dicarboxylic acids ... 

The techniques discussed in this paper can be used not only for solving the problem of magneto-acoustic or piezo-electric ringing, but also for cancelling the residual ringing in the coil, the secondary ringing caused by the Q-switch system or any other spurious signals. 

No synthetically significant (< eight-membered) secondary rings. 

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