Nucleophilic substitutions, including SN1 and SN2, are classical and reliable reactions, but a serious drawback is their intolerance for both bulky nucleophiles and chiral tertiary alkyl electrophiles for the synthesis of a chiral quaternary carbon center. An SRN1 reaction via a radical species is another conventional method used to carry out substitution reactions of bulky nucleophiles and alkyl halides, but chiral tertiary alkyl electrophiles cannot be used. Therefore, a stereospecific nucleophilic substitution reaction using chiral tertiary alkyl electrophiles and bulky nucleophiles has not yet been well studied. In this paper, we describe the reaction of tertiary alkyl alcohols and non‐chiral or chiral α‐bromocarboxamides as a tertiary alkyl source for the formation of congested ether compounds possessing two different tertiary alkyl groups on the oxygen atom with stereoretention.

A stereospecific nucleophilic substitution between tertiary alkyl bromides and tertiary alkyl alcohols is described in the Research Article on page 4329 by Toshiki Nokami, Takashi Koike, Manabu Abe, Eiji Shirakawa, Takashi Nishikata, and co‐workers. The entering alcohol formally attacks the C−Br bond to undergo a retentive substitution with formation of tertiary alkyl ethers.

Nucleophilic substitutions, including SN1 and SN2, are classical and reliable reactions, but a serious drawback is their intolerance for both bulky nucleophiles and chiral tertiary alkyl electrophiles for the synthesis of a chiral quaternary carbon center. An SRN1 reaction via a radical species is another conventional method used to carry out substitution reactions of bulky nucleophiles and alkyl halides, but chiral tertiary alkyl electrophiles cannot be used. Therefore, a stereospecific nucleophilic substitution reaction using chiral tertiary alkyl electrophiles and bulky nucleophiles has not yet been well studied. In this paper, we describe the reaction of tertiary alkyl alcohols and non‐chiral or chiral α‐bromocarboxamides as a tertiary alkyl source for the formation of congested ether compounds possessing two different tertiary alkyl groups on the oxygen atom with stereoretention.

Eine stereospezifische nukleophile Substitution zwischen tertiären Alkylbromiden und tertiären Alkylalkoholen wird auf S. 4375 im Forschungsartikel von Toshiki Nokami, Takashi Koike, Manabu Abe, Eiji Shirakawa, Takashi Nishikata und Mitarbeitern beschrieben. Der eintretende Alkohol greift formal die C‐Br‐Bindung an, um eine retentive Substitution unter Bildung von tertiären Alkylethern einzugehen.

This paper deals with the seawater exchange caused by density gradient between the outer bay and inner bay using density profile around the bay mouth and velocity profile above the mound. It is revealed that the mechanism of seawater exchange is greatly influenced with the density intrusion depending on the horizontal density gradient. When the density of the outer bay is smaller than the inner bay, the seawater exchange occurs in the upper layer, and cannot be expected in the lower water. But, when the density of the outer bay becomes bigger than the inner bay, for example, after coming typhoon, seawater exchange is accelerated by two types of sewater exchange mechanism. One is intrusion of the outer bay water, the other is out flow due to internal wave.