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October 28, 2026CompoundingHHS lets 503A pharmacies compound six peptides under an interim enforcement discretion policyOctober 28, 2026Trial resultRetatrutide beats Ozempic on blood sugar and weight in head-to-head TRANSCEND-T2D-2 trialOctober 23, 2026FDA approvalFDA extends once-weekly insulin icodec (Awiqli) to children 10 and older with type 2 diabetesOctober 21, 2026CompoundingCitizen petition asks FDA not to allow compounding of seven peptides reviewed by its advisory committeeOctober 1, 2026Trial resultSurvodutide SYNCHRONIZE-2 phase 3 results in obesity with type 2 diabetes published in NEJMSeptember 30, 2026Trial resultEloraTZP (eloralintide plus tirzepatide) phase 2 results presented at EASD 2026September 30, 2026Trial resultOrforglipron ACHIEVE-4 cardiovascular safety trial published in The LancetSeptember 29, 2026Trial resultFull TRIUMPH-2 retatrutide results published in The LancetSeptember 24, 2026FDA approvalFDA approves insulin efsitora alfa (Onswik), a once-weekly basal insulin for type 2 diabetesSeptember 21, 2026WADAWADA publishes 2027 Prohibited List, naming peptides as examples of non-approved substances

October 28, 2026CompoundingHHS lets 503A pharmacies compound six peptides under an interim enforcement discretion policyOctober 28, 2026Trial resultRetatrutide beats Ozempic on blood sugar and weight in head-to-head TRANSCEND-T2D-2 trialOctober 23, 2026FDA approvalFDA extends once-weekly insulin icodec (Awiqli) to children 10 and older with type 2 diabetesOctober 21, 2026CompoundingCitizen petition asks FDA not to allow compounding of seven peptides reviewed by its advisory committeeOctober 1, 2026Trial resultSurvodutide SYNCHRONIZE-2 phase 3 results in obesity with type 2 diabetes published in NEJMSeptember 30, 2026Trial resultEloraTZP (eloralintide plus tirzepatide) phase 2 results presented at EASD 2026September 30, 2026Trial resultOrforglipron ACHIEVE-4 cardiovascular safety trial published in The LancetSeptember 29, 2026Trial resultFull TRIUMPH-2 retatrutide results published in The LancetSeptember 24, 2026FDA approvalFDA approves insulin efsitora alfa (Onswik), a once-weekly basal insulin for type 2 diabetesSeptember 21, 2026WADAWADA publishes 2027 Prohibited List, naming peptides as examples of non-approved substances

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Making peptides · Part 2: Solid-phase peptide synthesis

Protecting groups, Boc and Fmoc

Lesson 4.2.2 · 6 min read · Advanced plan

What you'll learn

Protecting groups are temporary chemical caps that keep amino acids from reacting in the wrong places.
SPPS uses temporary caps on the chain's amine end and permanent caps on side chains, removed under different ("orthogonal") conditions.
Boc chemistry removes its cap with acid and relies on harsh hydrogen fluoride, which Fmoc avoids; it's now used mainly for specialist work.
Fmoc chemistry removes its cap with a mild base and is the method of choice for most synthetic peptides.

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