Total synthesis of (.+-.)-aspirochlorine

Abstract

The material in this chapter is divided into three sections. The first section is intended to provide a general overview of the physical/chemical properties common to all epidithiodioxopiperazines. The second section introduces the structures of naturally occurring epipolythiodioxopiperazines and related metabolites which have been characterized. Lastly, the third section is devoted to a discussion of the more interesting • biosyntheses of several of the metabolites. Physical/chemical Properties of epipolythiodioxopiperazinesThe epipolythiodioxopiperazine ring system possesses a variety of physical properties which ultimately control the chemical reactivity of this unusual ring system. The disulfide bridge is highly strained and is easily reduced with mild reducing agents such as sodium borohydride. The strain inherent in the disulfides is a direct consequence of the small CSSC dihedral angles found in the epidithiodioxopiperazines compared to CSSC dihedral angles found in acyclic disulfides. Normal dihedral angles of 7 4-105° are often observed in acyclic disulfides, 4 whereas the CSSC dihedral angles present in the epidithiodioxopiperazines range from 8-18°.2d Analysis of X-ray structures indicate the S-S bonds in the epidithiodioxopiperazines are longer (2.059 vs 2.03-2.05 A) than in acyclic disulfides. 2d Analysis of the X-ray structures of the epidithiodioxopiperazines also indicates the Blsdethio-(dlmethylthio)acetylaranotln (LL-S88~)

Epidithiodioxopiperazines. occurrence, synthesis and biogenesis

“…125 4-chloro-resorcinol ( 181 ) was converted to the benzaldehyde via a Gatterman formylation, protected as the MOM ether, and cyclized to coumarilic acid derivative ( 182 , Scheme 13). Schotten–Baumann coupling of the glycine derivative was followed by protection of the phenol to afford 183 in excellent yield.…”

Divergent Synthesis of Disulfanes and Benzenesulfonothioates Bearing 2‐Aminofurans From N‐Tosylhydrazone‐Bearing Thiocarbamates

“…[6a] In addition, the purine nucleoside disulfane III is an important precursor in vinylthiol chemistry, [6c] and the uridine disulfane IV is as table precursor to potential mechanistic probes for ribonucleotide reductases (RNRs). [7] The highly stereoselective sulfur migration (Scheme 2a,s trategy b), [8] and the treatment of the O-(trifluoromethanesulfonyl)adenosine with potassium thioacetate (Scheme 2a,s trategy c). So far only af ew synthetic strategies have been developed for the synthesis of these molecules:f or example, the cycloaddition of ab enzofuran hydroxamic ester to form the spiro[benzafuran-2(3H),2'-piperazine] ring system, with subsequent SÀSb ond formation (Scheme 2a,s trategy a; 4-5 steps required from benzofuran hydroxamic ester).…”

Synthetic Approach of Thermally Tunable Nature‐Mimetic Polypeptides from N‐Protected Alternating Peptoids

“…With the limitation on the synthesis of artificial alternating peptide in mind, we have tried to find the other protecting group. As part of the attempts, we synthesized o ‐nitrobenzyl group‐containing alternating peptoids (see Supporting Information) and considerably studied photo‐induced cleavage of o ‐nitrobenzyl group . However, the deprotection ratio was up to ≈50%.…”