Pfizer — US 4,041,163
"The pyrimido[2,1-b]benzothiazole ring system was first reported by Antaki, et al., J. Chem. Soc., 551 (1951)."
Declarative. No hedge. First.
The following are selected examples of how independent third parties described the work of H. B. F. Antaki — patent attorneys writing under legal obligation to accuracy, review authors summarising the state of a field, encyclopaedia editors, and researchers building on his chemistry. None had any obligation to mention him. These are their words, not ours.
Patent text is in the public domain. Every word in a patent filing is deliberate, reviewed by attorneys, and legally consequential.
"The pyrimido[2,1-b]benzothiazole ring system was first reported by Antaki, et al., J. Chem. Soc., 551 (1951)."
Declarative. No hedge. First.
"The synthesis of a 1H-pyrimido[1,2-a]quinoline appears to have first been reported by Antaki et al., J. Chem. Soc., pp. 551–555 (1951)."
Followed by a detailed paragraph-by-paragraph technical summary of both the 1951 J. Chem. Soc. and the 1958 J. Am. Chem. Soc. papers, closing with: "The compound demonstrated antischistosomal action." Pfizer documented not only the synthesis but the biological programme behind it.
Cites 1951 J. Chem. Soc. and 1958 J. Am. Chem. Soc. Uses the word "first" in the Description of Prior Art. Israeli counterpart IL49924. Filed within weeks of a Bristol-Myers patent independently citing the same papers — two major pharmaceutical companies, independently, reaching back to the same source.
"Some examples of the acrylates of formula VI are disclosed by Antaki in J. Amer. Chem. Soc., 80, 3066 (1958)."
"Disclosed by" — Hekmat named as the original disclosure of those specific compounds. Listed first; Nishigaki 1971 listed second.
"The compounds of formula I wherein R is 5-nitro-2-furyl, 3-nitrophenyl and 4-nitrophenyl are known, for example from… Antaki, J. Chem. Soc., 4877 (1963)."
"Suitable reaction conditions are also reported by Antaki in J. Chem. Soc., 4877 (1963)."
Out of all scientific literature available, ICI selected only four non-patent references. Antaki 1963 was one of them — cited twice, for both the compounds and the conditions. The same patent family cites him again in EP 0539153.
"Suitable reaction conditions are also reported by Antaki in J. Chem. Soc., 4877 (1963)."
Validated as reliable procedural authority — "suitable" is the language of a practitioner directing another practitioner to a trusted source.
Antaki 1963 appears in the Non-Patent Citations, marked with an asterisk: examiner-supplied, not applicant-supplied. The USPTO examiner independently reached back to his paper and placed it on the record. Meanwhile the patent describes their own compound as "unexpectedly capable," with "surprisingly good potency" and "chemical stability superior" — language used in patent law to establish non-obviousness over prior art. The prior art the examiner placed on record was Antaki.
One non-patent citation in the entire document. Out of all scientific literature available — one paper. His: Antaki, J. Chem. Soc., 551 (1951).
"hexahydroquinoline derivatives aroused our interest."
Friedrich Bossert and Wulf Vater, inventors of nifedipine. Reference 7 in that paper is Antaki, J. Chem. Soc., 1963. He appears again as reference 13, when the authors place his work in the historical synthetic lineage alongside the classic Hantzsch and Knoevenagel reactions. This review has been cited thousands of times.
"In 1951 Antaki and Petrow came to the conclusion that the poor yield of the pyrido[1,2-a]pyrimidines in the reaction of 2-aminopyridines and acylacetates is ascribed to a rearrangement reaction that the intermediate 2-acylacetamidopyridines undergo."
"Products of 4-methylpyridine and ethoxymethylene cyanoacetate in various ring closure reactions were first described by Antaki."
"Antaki concluded that the absorption band for the 2-oxo-2H- and 4-oxo-4H-pyrido[1,2-a]pyrimidines in the range 300–400 nm can be ascribed to the 2-imino-1-substituted-1,2-dihydropyridine chromophore, and the band in the interval 250–270 nm to the C=C–C=O chromophore of the molecules."
The canonical review of pyrido[1,2-a]pyrimidine chemistry. Antaki is discussed analytically across multiple pages — as structural corrector, priority figure, first descriptor of ring-closure products, and spectroscopic analyst. His name appears in the running text, not only in the reference list.
"Antaki and Petrow showed that the product was in fact the 2-methyl-4-keto isomer… by virtue of its alternate synthesis from 2-bromopyridine and ethyl β-aminocrotonate."
Received October 3, 1968. Antaki and Petrow are cited by name in the running text — without a reference number. In a paper with a numbered bibliography, that is the form of citation reserved for foundational authority that needs no number.
"Antaki and Petrow discovered that when ethyl β-aminocrotonate was heated with 2-bromopyridine, a cyclized compound was obtained… Antaki formulated their product as 2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one."
Investigating the reaction of 2-aminopyridine with diketene, Kato and colleagues reproduced the route directly — "employing the procedure given for the 4-one derivative reported by Antaki and Petrow" — and confirmed by mass, NMR, IR and UV spectra that the product was the 4-one, upholding Antaki's assignment against a contrary proposal published in 1969.
"Antaki and Petrow discovered that when ethyl β-aminocrotonate was heated with 2-bromopyridine at 180–200° for several hours, a cyclized compound was obtained… Antaki and Petrow formulated their product as XVII."
"Ultraviolet Spectra and Structures of the Pyrido[1,2-a]pyrimidones." Within a year of the 1951 paper, Adams and Pachter independently confirmed the structure by ultraviolet spectroscopy and credited Antaki and Petrow with both the synthesis and the structural assignment. They documented his improved route as well: "Antaki and Petrow synthesized XVII in good yield by heating 2-aminopyridine with ethyl β-aminocrotonate."
Antaki 1958 J. Am. Chem. Soc. is listed as Reference 1(a) in the entry for Ethyl Ethoxymethyleneacetoacetate — the most consulted synthetic chemistry reference in the discipline. DOI: 10.1002/047084289X.re082
Reference 8 in the paper body and Table VIII footnote e: the Kodak team actively prepared compounds using the Antaki & Petrow procedure. Beyond citation — active laboratory use of his method by a major industrial research laboratory.
Surveying the entire literature on 4-azabenzo[c]quinolizine derivatives, the authors find only two prior compounds synthesised in the class. Both are Hekmat's: Antaki & Petrow 1951 and Antaki 1958. Their paper exists to go beyond where he stopped.
"Of a series of quinolino-, indolo-, pyrrolo-, thiazolo- and triazafluoreno-steroids prepared as potential antimicrobial agents… (Antaki and Petrow, 1951)."
His compounds reached the pharmacological literature within a decade of publication and were independently subjected to biological screening by a university research group — evidence that his work was read and acted upon beyond the chemistry community.
"The practicality and elegance of the Antaki synthesis, particularly its one-step approach, make it highly relevant not only from a historical standpoint but also for contemporary medicinal chemistry and drug discovery applications. It was therefore important to recognize his work alongside other foundational methods in the field."
Written in personal correspondence after the publication of Oduselu et al., Frontiers in Chemistry, 2026 — the paper that formally names the Antaki synthesis as a classical multicomponent reaction alongside the Hantzsch and Stankevich methods. DOI: 10.3389/fchem.2026.1769586