Au-Catalyzed Synthesis of (1Z,3E)-2-Pivaloxy-1,3-Dienes from Propargylic Pivalates

Abstract

Propargylic pivalates with electronically unbiased internal alkynes are selectively transformed into (1Z,3E)-2-pivaloxy-1,3-dienes containing various functionalities. The unusual selectivity of 1,2-acyloxy migration over the structurally preferred 3,3-rearrangement is realized. This reaction is highly stereoselective and offers rapid access to dienes for one-pot intra-/intermolecular Diels-Alder reactions either under thermal conditions or with Lewis acid catalysis.

Gold Catalysis: Isolation of Vinylgold Complexes Derived from Alkynes

“…Similar observations have been made for the related propargylic carboxylates. [12] The other difference between this and previous work is the stability of the organogold intermediates. In analogy to 5, aqueous acetonitrile protodemetallated 4 a to 3 a at room temperature.…”

CO Cross‐Coupling of Activated Aryl and Heteroaryl Halides with Aliphatic Alcohols

“…Unexpectedly, an alkyne was concurrently transformed to the 1,3-diene 3 ci, presumably by means of 1,2-aryloxy migration (Table 3, entry 8). [11] Complete regioselectivity was observed for primary over secondary over tertiary alcohols (Table 3, entries 6 and 14). [12] Cat., 1 b, 2 a, Cs 2 CO 3 0 9 9 6…”

Gold‐Katalyse: Isolierung von Vinylgold‐Komplexen ausgehend von Alkinen

“…Während die terminalen Derivate von 1 (mit R 2 = H) glatt zu den Alkylidenoxazolinen 2 oder den isomeren aromatischen Oxazolen 2' reagieren, [3] setzten verschiedene Gold(I)-und Gold(III)-Katalysatoren die internen Alkine nicht effizient um, wie für 1 a (R 1 = Ph, R 2 = Me) in Tabelle 1 [8] Um diese als stabile Verbindungen zu erhalten, variierten wir sowohl das Lösungsmittel 11,12,15),Benzol (Nr. 7,13), Toluol (Nr.…”

“…¾hnliche Beobachtungen wurden für die verwandten Propargylcarboxylate gemacht. [12] Der andere Unterschied zu vorherigen Arbeiten ist die Stabilität der Organogold-Zwischenstufe. In Analogie zu 5 protodemetallierte wässriges Acetonitril bei Raumtemperatur auch 4 a zu 3 a.…”