The Synthesis of Condensed Ring Compounds. VIII. Further Applications of the Dienyne Double Addition Reaction¹

Abstract

Rings by the Dienyne Double Addition Reaction 1311 bath at 140°for eight hours. The product was isolated as the free base by crystallization from 50% ethanol and water; yield, 2.0 g. (80%).Other Heterocyclic Substituted Aminoquinaldines.-4-Chloro-6-methoxyquinaldine (0.02 mole) was mixed well with 0.022 mole of the desired heterocyclic amine, i. e., 8aminoquinoline, 8-amino-6-methoxyquinoline, thionine (0.011 mole), and 5-aminoindazole. The reaction mixture in each case was heated in an oil-bath at 160-1750 for three hours. The products were isolated and purified by washing the residues with 5% sodium hydroxide then numerous crystallizations from 90% ethanol; yields, approximately 60 to 70%. Summary A. relatively simple and economical process for the preparation of basically substituted propylamines has been reported.4-Chloro-6-methoxyquinaldine has been condensed with a few basically substituted aliphatic amines and several heterocyclic amines to give the corresponding 4-substituted quinaldines.

Concerted vs Stepwise Mechanisms in Dehydro-Diels–Alder Reactions

“…Scheme 2 presents selected examples of this reaction as a cycloaddition or a cycloreversion. 29,68,69 Additional examples are cited in the recent review by Wessig and Muller. 22 The results of our calculations on enyne−ene cycloadditions are presented in Scheme 3, where energetics are summarized relative to reactants.…”

The Diels–Alder Reaction in Steroid Synthesis

“…were made in the 1940s and 1950s, [160][161][162][163][164] and an isolated report appeared in 1996. 165 The most recent investigation of this transformation was published by Paddon-Row and Sherburn in 2009.…”

A + D → Ad → Abcd

“…Condensation of 63 (R = H, R' = Me, n = 2) with maleic anhydride at 130° gave a 1.9% yield of 62, the actual stereochemistry of which was not determined [56]. A similar reaction of 63 (R = OMe, R' = H, n = l) with dimethyl fumarate produced 64 in moderate (45%) yield, but again the stereochemistry was unspecified [57]. It was determined that better yields were obtained when n = 2 and when R' = H, thus dampening hopes of application to steroid total synthesis.…”

“…Also outlined in Scheme 8-6 is a synthetic sequence remarkable for its simplicity [54][55][56][57][58]. The starting dienynes 63 were readily obtained from dehydration of the corresponding acetylenic glycols which were in turn prepared from acetylene and the appropriate cycloalkanones [59].…”