Fusion atoms

Most of the (5,5) (2N2)-fused heterocyclic systems are fully substituted aromatic systems and therefore they do not have any hydrogens attached to the ring. Very little is reported on C-unsubstituted compounds. Methine groups are generally part of a ring azomethine moiety and are either linked to a fusion atom C or N or to a nonfusion atom N or S (Table 1). 

Penicillins are the most widely used of the clinical antibiotics. They contain in their structures an unusual fused ring system in which a four-membered P-lactam ring is fused onto a five-membered thiazolidine. Both rings are heterocyclic, and one of the ring fusion atoms is nitrogen. These heteroatoms do not alter our understanding of molecular shape, since we can consider that they also have an essentially tetrahedral array of bonds or lone pair electrons (see Section 2.6.3). 

The cis fusion in which one of the fusion atoms is nitrogen merely indicates that the nitrogen lone pair electrons occupy the remaining part of the tetrahedral array. It does, however, mean that inversion at the nitrogen atom (see Section 3.4.1) is not possible, since that would hypothetically result in formation of the impossible fran -fused system. The ring fusion has thus frozen the nitrogen atom into one configuration. 

JOC5160). Benzylmagnesium chloride is exceptional as it consistently attacks at C-4 even when this is a ring-fusion atom as in l,3-dimethyl-5,6,7,8-tetrahydro-2-benzopyrylium perchlorate (40) <64LA(678)183>. 

Atomic (or Nuclear) Bomb. A weapon invented during WWII and developed in the United States as a joint effort with the British and Canadian governments. It utilizes for its destructive effect the energy of an Atomic or Nuclear Explosion (qv). Since atomic explosions are of two types, fission and fusion, atomic bombs are of. corresponding types. However, it has been necessary to first initiate an atomic explosion with a nuclear fission reaction in order to bring about the conditions under which a nuclear fusion(thermonuclear) reaction can occur. 

ORNL Controlled Fusion Atomic Data Centre website www-cfadc. phy. ornl. gov... 

Prioritize stereocenters such as acychc double bonds, ring fusion atoms, ring bridgehead atoms, etc. 

Methine groups are generally part of a ring azomethine moiety and are either linked to a fusion atom (C or N) or to a nonfusion atom (N or S) (Table 2). 

X (fusion atom) N DMSO-d 7.2-7.9 (under arom. H) 93MI 807-01... 

N CHj N fusion atom X nonfusion atom X = N CDClj 5.55-5.9 92PS(70)99... 

The Oak Ridge National Laboratory (ORNL) Controlled Fusion Atomic Data Center ... 

Fusion (atomic) n. A nuclear reaction involving the combination of smaller atomic nuclei or particles into larger ones with the release of energy from mass transformation. This is also called a thermonuclear reaction by reason of the extremely high temperature required to initiate it. 

Fig. 15.14 A schematic representation of single-atom fusion between two cages. Only the fusion atom is shown explicitly.

If all the above allow two choices, give the lowest number to the first fusion atom. 

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