{"id":229942,"date":"2025-06-08T16:33:10","date_gmt":"2025-06-08T16:33:10","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=229942"},"modified":"2025-06-08T16:33:12","modified_gmt":"2025-06-08T16:33:12","slug":"what-are-the-two-starting-materials-for-robinson-annulation","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/08\/what-are-the-two-starting-materials-for-robinson-annulation\/","title":{"rendered":"What are the two starting materials for Robinson annulation"},"content":{"rendered":"\n

What are the two starting materials for Robinson annulation? Multiple Choice a) An \u00ce\u00b1,\u00ce\u00b2-Unsaturated carbonyl compound and an enolate b) Ketoester and an enolate c) 1,5-Dicarbonyl compound and an enolate d) 1,3-Dicarbonyl compound and an enolate<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

Correct Answer: a) An \u03b1,\u03b2-Unsaturated carbonyl compound and an enolate<\/strong><\/p>\n\n\n\n

\n\n\n\n

Explanation <\/h3>\n\n\n\n

The Robinson annulation<\/strong> is a classic organic reaction that forms six-membered rings and is particularly useful in the synthesis of complex cyclic molecules such as steroids and natural products. The reaction is a combination of two fundamental reactions<\/strong>: the Michael addition<\/strong> and the intramolecular aldol condensation<\/strong>.<\/p>\n\n\n\n

The two starting materials<\/strong> required for a Robinson annulation are:<\/p>\n\n\n\n

    \n
  • An \u03b1,\u03b2-unsaturated carbonyl compound<\/strong> (commonly a ketone or aldehyde with a conjugated double bond),<\/li>\n\n\n\n
  • An enolate<\/strong> (usually derived from a 1,3-dicarbonyl compound such as a \u03b2-ketoester or \u03b2-diketone).<\/li>\n<\/ul>\n\n\n\n

    Here\u2019s how the reaction proceeds:<\/p>\n\n\n\n

      \n
    1. Michael Addition<\/strong>: The enolate (nucleophile) attacks the \u03b2-carbon of the \u03b1,\u03b2-unsaturated carbonyl compound (electrophile). This forms a 1,5-dicarbonyl intermediate via conjugate (1,4-) addition.<\/li>\n\n\n\n
    2. Aldol Condensation<\/strong>: The resulting 1,5-dicarbonyl compound undergoes an intramolecular aldol condensation. The enolate formed from one carbonyl attacks the other carbonyl group, forming a new carbon-carbon bond and resulting in ring formation.<\/li>\n\n\n\n
    3. Dehydration<\/strong>: The aldol product typically loses water, forming a double bond and resulting in a conjugated cyclic enone product.<\/li>\n<\/ol>\n\n\n\n

      Why the other choices are incorrect:<\/h3>\n\n\n\n
        \n
      • b) Ketoester and an enolate<\/strong>: This is too vague. While a ketoester may form an enolate, it must react with an \u03b1,\u03b2-unsaturated carbonyl to qualify for Robinson annulation.<\/li>\n\n\n\n
      • c) 1,5-Dicarbonyl compound and an enolate<\/strong>: The 1,5-dicarbonyl compound is typically an intermediate<\/strong>, not a starting material.<\/li>\n\n\n\n
      • d) 1,3-Dicarbonyl compound and an enolate<\/strong>: A 1,3-dicarbonyl forms the enolate, but another reactant (\u03b1,\u03b2-unsaturated carbonyl) is required.<\/li>\n<\/ul>\n\n\n\n

        Thus, option (a)<\/strong> accurately describes the necessary starting materials for the Robinson annulation.<\/p>\n\n\n\n

        \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

        What are the two starting materials for Robinson annulation? Multiple Choice a) An \u00ce\u00b1,\u00ce\u00b2-Unsaturated carbonyl compound and an enolate b) Ketoester and an enolate c) 1,5-Dicarbonyl compound and an enolate d) 1,3-Dicarbonyl compound and an enolate The Correct Answer and Explanation is: Correct Answer: a) An \u03b1,\u03b2-Unsaturated carbonyl compound and an enolate Explanation The Robinson […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-229942","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/229942","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=229942"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/229942\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=229942"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=229942"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=229942"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}